Protecting group - Knowledge (XXG)

895: 1760: 883: 1959:. The procedure begins actually with redox chemistry at the protected phosphorus atom. A tricoordinate phosphorus, used on account of the high reactivity, is tagged with a cyanoethyl protecting group on a free oxygen. After the coupling step follows an oxidation to phosphate, whereby the protecting group stays attached. Free OH-groups, which did not react in the coupling step, are acetylated in an intermediate step. These additionally-introduced protecting groups then inhibit, that these OH-groups might couple in the next cycle. 447: 1652: 1805: 1723: 1819: 407: 1433: 540: 247: 1868: 33: 168: 266: 1925: 1284: 1708: 400: 1276: 513: 869: 1963: 1906: 235:

regarding the reaction conditions such as reaction time, temperature and reagents can be standardized so that they are carried out by a machine, while yields of well over 99% can be achieved. Otherwise, the separation of the resulting mixture of reaction products is virtually impossible (see also

1488:

Many groups can suffice for the alcoholic component, and the specific cleaving conditions are contrariwise generally quite similar: each ester can be hydrolyzed in a basic water-alcohol solution. Instead, most ester protecting groups vary in how mildly they can be formed from the original acid.

3039:

András Lipták, János Imre, János Harangi, Pál Nánási, András Neszmélyi: "Chemo-, stereo- and regioselective hydrogenolysis of carbohydrate benzylidene acetals. Synthesis of benzyl ethers of benzyl α-D-, methyl β-D-mannopyranosides and benzyl α-D-rhamnopyranoside by ring cleavage of benzylidene

1647:: the transformation of an alkene with a diene leads to a cyclic alkene, which is nevertheless similarly endangered by electrophilic attack as the original alkene. The cleavage of a protecting diene proceeds thermically, for the Diels-Alder reaction is a reversible (equilibrium) reaction. 3535:

John N. Haseltine, Maria Paz Cabal, Nathan B. Mantlo, Nobuharu Iwasawa, Dennis S. Yamashita, Robert S. Coleman, Samuel J. Danishefsky, Gayle K. Schulte: "Total synthesis of calicheamicinone: new arrangements for actuation of the reductive cycloaromatization of aglycon congeners", in:

2292:

Morris J. Robins, Vicente Samano, Mark D. Johnson: "Nucleic acid-related compounds. 58. Periodinane oxidation, selective primary deprotection, and remarkably stereoselective reduction of tert-butyldimethylsilyl-protected ribonucleosides. Synthesis of 9-(β-D-xylofuranosyl)adenine or

1793:

does not employ protective groups. As an alternative, Baran presented a novel protective-group free synthesis of the compound hapalindole U. The previously published synthesis according to Baran, contained 20 steps with multiple protective group manipulations (two confirmed):

1321:

Cyclic acetals are very much more stable against acid hydrolysis than acyclic acetals. Consequently acyclic acetals are used practically only when a very mild cleavage is required or when two different protected carbonyl groups must be differentiated in their liberation.

158:

As a rule, the introduction of a protecting group is straightforward. The difficulties honestly lie in their stability and in selective removal. Apparent problems in synthesis strategies with protecting groups are rarely documented in the academic literature.

2768:

Karel F. Bernady, M. Brawner Floyd, John F. Poletto, Martin J. Weiss: "Prostaglandins and congeners. 20. Synthesis of prostaglandins via conjugate addition of lithium trans-1-alkenyltrialkylalanate reagents. A novel reagent for conjugate 1,4-additions", in:

1955:‑butyl group (acidic cleavage) and diverse protecting groups for functional groups on the amino acid side-chains are used. Up to four different protecting groups per nucleobase are used for the automated synthesis of DNA and RNA sequences in the 118:

Protecting groups are more common in small-scale laboratory work and initial development than in industrial production because they add additional steps and material costs. However, compounds with repetitive functional groups – generally,

1898:'s research group. Here 42 functional groups (39 hydroxyls, one diol, an amine group, and a carboxylic acid) required protection. These proceeded through 8 different protecting groups (a methyl ester, five acetals, 20 TBDMS esters, nine 3630:

Yves Rubin, Carolyn B. Knobler, Francois Diederich: "Precursors to the cyclocarbons: from 3,4-dialkynyl-3-cyclobutene-1,2-diones and 3,4-dialkynyl-3-cyclobutene-1,2-diols to cyclobutenodehydroannulenes and higher oxides of carbon", in:

1770:

for deprotection of the right-side ester group is reduced and it stays intact. Significantly by placing the deuterium atoms next to the left-side ester group or by changing the wavelength to 254 nm the other monoarene is obtained.

2374:

Leo A. Paquette, Annette M. Doherty, Christopher M. Rayner: "Total synthesis of furanocembranolides. 1. Stereocontrolled preparation of key heterocyclic building blocks and assembly of a complete seco-pseudopterane framework", in:

4191:

Martin Banwell, David Hockless, Bevyn Jarrott, Brian Kelly, Andrew Knill, Robert Longmore, Gregory Simpson: "Chemoenzymatic approaches to the decahydro-as-indacene cores associated with the spinosyn class of insecticide", in:

1700:) and subsequently reaction with chlorotrimethylsilane to a terminally TMS-protected alkyne. Cleavage follows hydrolytically – with potassium carbonate in methanol – or with fluoride ions like for example with 3011:

R.E. Ireland, D.W. Norbeck: "Convergent synthesis of polyether ionophore antibiotics: the synthesis of the monensin bis(tetrahydrofuran) via the Claisen rearrangement of an ester enolate with a β-leaving group", in:

1255:

The most common protecting groups for carbonyls are acetals and typically cyclic acetals with diols. The runners-up used are also cyclic acetals with 1,2‑hydroxythiols or dithioglycols – the so-called

1687:

For alkynes there are in any case two types of protecting groups. For terminal alkynes it is sometimes important to mask the acidic hydrogen atom. This normally proceeds from deprotonation (via a strong base like

1780:

The use of protective groups is pervasive but not without criticism. In practical terms their use adds two steps (protection-deprotection sequence) to a synthesis, either or both of which can dramatically lower

352:; thus silicon protecting groups are almost invariably removed by fluoride ions. Each type of counterion, i.e. cleavage reagent, can also selectively cleave different silicon protecting groups depending on 535:

Aliphatic methyl ethers cleave with difficulty and only under drastic conditions, so that these are in general only used with quinonic phenols. However, hemiacetals and acetals are much easier to cleave.

102:

groups, and cannot be discouraged by any means. When an ester must be reduced in the presence of a carbonyl, hydride attack on the carbonyl must be prevented. One way to do so converts the carbonyl into an

4163:

Hideyuki Tanaka, Takashi Kamikubo, Naoyuki Yoshida, Hideki Sakagami, Takahiko Taniguchi, Kunio Ogasawara: "Enantio- and Diastereocontrolled Synthesis of (−)-Iridolactone and (+)-Pedicularis-lactone", in:

709: — Comparable stability to MOM, MEM und SEM, but also admits reductive removal: sodium in liquid ammonia, catalytic hydrogenation (palladium hydroxide on activated carbon), or Raney nickel in ethanol 2149:

Tod K Jones, Robert A. Reamer, Richard Desmond, Sander G. Mills: "Chemistry of tricarbonyl hemiketals and application of Evans technology to the total synthesis of the immunosuppressant (−)-FK-506", in:

2931:

Toshiyuki Kan, Masaru Hashimoto, Mitsutoshi Yanagiya, Haruhisa Shirahama: "Effective deprotection of 2-(trimethylsilylethoxy)methylated alcohols (SEM ethers). Synthesis of thyrsiferyl-23 acetate", in:

4136:

Antonius J. H. Klunder, Jie Zhu, Binne Zwanenburg: "The Concept of Transient Chirality in the Stereoselective Synthesis of Functionalized Cycloalkenes Applying the Retro-Diels-Alder Methodology", in:

2699:

Serge David, Annie Thieffry, Alain Veyrières: "A mild procedure for the regiospecific benzylation and allylation of polyhydroxy-compounds via their stannylene derivatives in non-polar solvents", in:

3170:

Robert M. Williams, Peter J. Sinclair, Dongguan Zhai, Daimo Chen: "Practical asymmetric syntheses of α-amino acids through carbon-carbon bond constructions on electrophilic glycine templates", in:

1913:

The introduction or modification of a protecting group occasionally influences the reactivity of the whole molecule. For example, diagrammed below is an excerpt of the synthesis of an analogue of

1396:-acetals with acid catalysis from a dithiol and the carbonyl compound. Because of the greater stability of thioacetals, the equilibirum lies on the side of the acetal. In contradistinction to the 772: — More labile than MEM and MOM to acid hydrolysis: 0.1 M hydrochloric acid in methanol, concentrated hydrofluoric acid in acetonitrile, boron trifluoride etherate in dichloromethane, or 3873:

Tainejiro Hiyama, Akihiro Kanakura, Hajime Yamamoto, Hitosi Nozaki: "General Route to α,β-unsaturated Aldehydes of Homoterpenoid and terpenoid Structure. Sythesis of JH-II and β-Sinensal", in:

1422:-acetals. Their formation follows analogously from the thioalcohol. Also their cleavage proceeds under similar conditions and predominantly through mercury(II) compounds in wet acetonitrile. 3388:

Juji Yoshimura, Shigeomi Horito, Hiroriobu Hashimoto: "Facile Synthesis of 2,3,4,6-Tetra-O-benzyl-D-glucopyranosylidene Acetals Using Trimethylsilyl Trifluoromethanesulfonate Catalyst", in:

2741:

Paul A. Wender, Carlos R. D. Correia: "Intramolecular photoinduced diene-diene cyaloadditions: a selective method for the synthesis of complex eight-membered rings and polyquinanes", in:

3508:

Samuel J. Danishefsky, Nathan B. Mantlo, Dennis S. Yamashita, Gayle. Schulte: "Concise route to the calichemicin-esperamicin series: the crystal structure of an aglycone prototype", in:

3576:

Peter Mohr, Nada Waespe-Šarčević, Christoph Tamm, Krystyna Gawronska, Jacek K. Gawronski: "A Study of Stereoselective Hydrolysis of Symmetrical Diesters with Pig Liver Esterase", in:

875:

An exceptional case appears with the benzylideneprotecting group,which also admits reductive cleavage. This proceeds either through catalytic hydrogenation or with the hydride donor

4020:

Timothy S. Butcher, Feng Zhou, Michael R. Detty: "Debrominations of vic-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications", in:

2478:

M.L. García, J. Pascual, L. Borràs, J.A. Andreu, E. Fos, D. Mauleón, G. Carganico, F. Arcamone: "Synthesis of new ether glycerophospholipids structurally related to modulator", in:

1759: 2958:

Joseph P. Marino, Scott L. Dax: "An efficient desilylation method for the generation of o-quinone methides: application to the synthesis of (+)- and (−)-hexahydrocannabinol", in:

3966:

Ahmed M. Tafesh, Jens Weiguny: "A Review of the Selective Catalytic Reduction of Aromatic Nitro Compounds into Aromatic Amines, Isocyanates, Carbamates, and Ureas Using CO", in:

620:-Butyldimethylsilyl (TBDMS or TBS) — Cleaved with acetic acid in tetrahydrofuran/water, Pyridinium tosylate in methanol, trifluoroacetic acid in water, hydrofluoric acid in 4533:

Synthetic studies of marine alkaloids hapalindoles. Part 2. Lithium aluminum hydride reduction of the electron-rich carbon-carbon double bond conjugated with the indole nucleus

3685:

G. Bauduin, D. Bondon, Y. Pietrasanta, B. Pucci: "Reactions de transcetalisation – II: Influence des facteurs steriques et electroniques sur les energies de cetalisation", in:

231:

A common example for this application, the Fmoc peptide synthesis, in which peptides are grown in solution and on solid phase, is very important. The protecting groups in

224:-butyl ether on the phenol group. The benzyl ester can be removed by hydrogenolysis, the fluorenylmethylenoxy group (Fmoc) by bases (such as piperidine), and the phenolic 246: 1291:

Overall, trans-acetalation plays a lesser role in forming protective acetals; they are formed as a rule from glycols through dehydration. Normally a simple glycol like

2558:

H. Nagaoka, W. Rutsch, G. Schmidt, H. Ito, M.R. Johnson, Y. Kishi: "Total synthesis of rifamycins. 1. Stereocontrolled synthesis of the aliphatic building block", in:

1943:

Protecting group chemistry finds itself an important application in the automated synthesis of peptides and nucleosides. The technique was introduced in the field of

3739:

M.P. Bosch, M. Pilar Bosch, Francisco Camps, Jose Coll, Angel Guerrero, Toshio Tatsuoka, Jerrold Meinwald: "A stereoselective total synthesis of (±)-muzigadial", in:

3442:

Kwan Soo Kim, Yang Heon Song, Bong Ho Lee, Chi Sun Hahn: "Efficient and selective cleavage of acetals and ketals using ferric chloride adsorbed on silica gel", in:

4360:

Rosa F. Lockwood, Kenneth M. Nicholas: "Transition metal-stabilized carbenium ions as synthetic intermediates. I. α- carbenium ions as propargylating agents", in:

879:(DIBAL). The cleavage with DIBAL deprotects one alcohol group, for the benzyl moiety stays as a benzyl ether on the second, sterically hindered hydroxy group. 3792:

Ulrich Schmidt, Thomas Beuttler, Albrecht Lieberknecht, Helmut Griesser: "Aminosäuren und peptide – XXXXII. Synthese von Chlamydocin + epi-Chlamydocin", in:

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ions is shown below. Here it is applied, that aldehydes are very much more activated carbonyls than ketones and that many addition reactions are reversible.

3993:

Evan L. Allred, Boyd R. Beck, Kent J. Voorhees: "Formation of carbon-carbon double bonds by the reaction of vicinal dihalides with sodium in ammonia", in:

641:‑Butyldiphenylsilyl (TBDPS) — Similar conditions to TBS but even longer reaction times (100–250× slower than TBS and 5–10× slower than TIPS) 4074:

Corrado Malanga, Serena Mannucci, Luciano Lardicci: "Carbon-halogen bond activation by nickel catalyst: Synthesis of alkenes, from 1,2-dihalides", in:

3603:

Théophile Tschamber, Nada Waespe-Šarčević, Christoph Tamm: "Stereocontrolled Synthesis of an Epimer of the C(19)-to-C(27) Segment of Rifamycin S", in:

4454:

Baran, Phil S.; Maimone, Thomas J.; Richter, Jeremy M. (22 March 2007). "Total synthesis of marine natural products without using protecting groups".

672: 4815: 2796:

Elias J. Corey, Haruki Niwa, Jochen Knolle: "Total synthesis of (S)-12-hydroxy-5,8,14-cis,-10-trans-eicosatetraenoic acid (Samuelsson's HETE)", in:

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exhibit very similar reactivities, a transformation that protects or deprotects a single hydroxy group must be possible for a successful synthesis.

292:

Many reaction conditions have been established that will cleave protecting groups. One can roughly distinguish between the following environments:

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David A. Evans, Stephen W. Kaldor, Todd K. Jones, Jon Clardy, Thomas J. Stout: "Total synthesis of the macrolide antibiotic cytovaricin", in:

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Festphasensynthese eines tumorassoziierten Sialyl-Tn-Antigen-Glycopeptids mit einer Partialsequenz aus dem "Tandem Repeat" des MUC-1-Mucins

894: 3415:

Bruce H. Lipshutz, Daniel Pollart, Joseph Monforte, Hiyoshizo Kotsuki: "Pd(II)-catalyzed acetal/ketal hydrolysis/exchange reactions", in:

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James A. Marshall, Joseph D. Trometer, Bruce E. Blough, Thomas D. Crute: "Stereochemistry of SN2' additions to acyclic vinyloxiranes", in

818:

Methyl ethers – Cleavage is by TMSI in dichloromethane or acetonitrile or chloroform. An alternative method to cleave methyl ethers is BBr

4826:

A user site excerpting the classic Greene and Wuts text regarding stability of a few key groups, from this reference's extensive tables.

1353:, which one begins with to form these acetals, have a very unpleasant stench and are poisonous, which severely limit their applications. 82:, specific parts of the molecules cannot survive the required reagents or chemical environments. These parts (functional groups) must be 2722:

Kaoru Fuji, Shigetoshi Nakano, Eiichi Fujita: "An Improved Method for Methoxymethylation of Alcohols under Mild Acidic Conditions", in:

216:

is a strategy allowing the specific deprotection of one protective group in a multiply-protected structure. For example, the amino acid

2320:

R. Roger F. Newton, Derek P. Reynolds, Colin F. Webb, Stanley M. Roberts: "A short and efficient total synthesis of (±) prostaglandin D

4840: 4665:

Merrifield, R. B.; Barany, G.; Cosand, W. L.; Engelhard, M.; Mojsov, S. (1977). "Proceedings of the 5th American Peptide Symposium".

2428:

Michel Bessodes, Dimitri Komiotis, Kostas Antonakis: "Rapid and selective detritylation of primary alcohols using formic acid", in:

841:) present for protecting-group chemistry a special class of alcohols. One can exploit the adjacency of two hydroxy groups, e.g. in 3197:

Glenn L. Stahl, Roderich Walter, Clarck W. Smith: "General procedure for the synthesis of mono-N-acylated 1,6-diaminohexanes", in:

2639:

W. Clark Still, Shizuaki Murata, Gilbert Revial, Kazuo Yoshihara: "Synthesis of the cytotoxic germacranolide eucannabinolide", in:

111:

for the carbonyl. After the hydride step is complete, aqueous acid removes the acetal, restoring the carbonyl. This step is called

3658:

Sunggak Kim, Yong Gil Kim, Deog-il Kim: "A novel method for selective dioxolanation of ketones in the presence of aldehydes", in:

2231:

James A. Marshall, Richard Sedrani: "A convergent, highly stereoselective synthesis of a C-11-C-21 subunit of the macbecins", in:

696:, (DMT) — Removed by weak acid. DMT group is widely used for protection of 5'-hydroxy group in nucleosides, particularly in 1838:

Although the use of protecting groups is not preferred in industrial syntheses, they are still used in industrial contexts, e.g.

1299:

is used for acetalation.Modern variants also use glycols, but with the hydroxyl hydrogens replaced with a trimethylsilyl group.

4836: 4704:

Serge L. Beaucage, Radhakrishman P. Iyer: "Advances in the Synthesis of Oligonucleotides by the Phosphoramidite Approach", in:

356:. The advantage of fluoride-labile protecting groups is that no other protecting group is attacked by the cleavage conditions. 4047:

C. J. Li, David N. Harpp: "Bis(triphenylstanyl)telluride a mild and selective reagent for telluration and debromination", in:

2181:-Di-O-methylelaiophylidene – preparation from elaiophylin and total synthesis from (R)-3-hydroxybutyrate and (S)-malate", in: 1632:‑1,2‑dibromoalkane: the regeneration of the alkene then follows with preservation of conformation via elemental 4783: 4279:

Barry J. Teobald: "The Nicholas reaction: the use of dicobalt hexacarbonyl-stabilised propargylic cations in synthesis", in:

4194: 2701: 2326: 718: 4101:

Byung Woo Yoo, Seo Hee Kim, Jun Ho Kim: "A Mild, Efficient, and Selective Debromination of vic-Dibromides to Alkenes with Cp

370:(30–40 °C). Because enzymes have very high substrate specificity, the method is quite rare, but extremely attractive. 1373:-acetals, very much stabler against acid hydrolysis. This enables the selective cleavage of the latter in the presence of 1735: 1079: 1045: 777: 2904:

Steven D. Burke, Gregory J. Pacofsky: "The ester enolate claisen rearrangement. Total synthesis of (±)-ethisolide", in:

769: 220:

could be protected as a benzyl ester on the carboxyl group, a fluorenylmethylenoxy carbamate on the amine group, and a

4858: 1846: 1701: 1593:– Removed by strong hot acid (pH < 1, T > 100 °C) or alkali (pH > 12, T > 100 °C), but not e.g. 1571:

Allyl esters — As with allyl ethers, also removed by diverse platinum complexes – connected with acid workup

1565: 1243: 876: 773: 625: 393: 2505:

Yuji Oikawa, Tadao Yoshioka, Osamu Yonemitsu: "Specific removal of o-methoxybenzyl protection by DDQ oxidation", in:

2177:

Dieter Seebach, Hak-Fun Chow, Richard F.W. Jackson, Marius A. Sutter, Suvit Thaisrivongs, Jürg Zimmermann: "(+)-11,11

574:(Piv) – Removed by acid, base or reductant agents. It is substantially more stable than other acyl protecting groups. 4637:

J.M. McClure, Samuel J. Danishefsky: "A novel Heck arylation reaction: rapid access to congeners of FR 900482", in:

981:

or Birch reduction, but have a decided drawback relative to the carbamates or amides: they retain a basic nitrogen.

4863: 2877:

Robert C. Gadwood, Renee M. Lett, Jane E. Wissinger: "Total synthesis of (±)-poitediol and (±)4-epipoitediol", in:

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Alkenes rarely need protection or are protected. They are as a rule only involved in undesired side reactions with

1404:‑acetal case, it is not needed to remove water from the reaction mixture in order to shift the equilibrium. 525: 504:, for these exhibit differential removal. Sterically hindered esters are less susceptible to nucleophilic attack: 144: 3224:

Naomi Sakai, Yasufumi Ohfune: "Total synthesis of galantin I. Acid-catalyzed cyclization of galantinic acid", in:

3900:

F. Huet, A. Lechevallier, M. Pellet, J.M. Conia: "Wet Silica Gel; A Convenient Reagent for Deacetalization", in:

3819:

Elias J. Corey, Plato A. Magriotis: "Total synthesis and absolute configuration of 7,20-diisocyanoadociane", in:

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in 1977. For peptide synthesis via automated machine, the orthogonality of the Fmoc group (basic cleavage), the

1887: 1665: 1594: 1119: 763: 697: 629: 87: 2457: 1302:

Acetals can be removed in acidic aqueous conditions. For those ends, the mineral acids are appropriate acids.

4333:

Richard E. Connor, Kenneth M. Nicholas: "Isolation, characterization, and stability of α- carbonium ions", in:

439:, which is activated through radiation with an appropriate wavelength and so can be removed. For examples the 1928:

Part of the synthesis of an analogue of Mitomycin C with modified reactivity through protecting-group exchange

882: 4816:

A further set of study notes in tutorial form, with guidance and comments, from Profs. Grossman and Cammers.

4111: 4225: 2041: 1948: 1689: 1557: 1084: 978: 706: 1876: 1754: 1307: 1064: 744: 389: 1843: 1222: 603: 4561: 4535: 4509: 3301: 1902:‑methoxybenzyl ethers, four benzoates, a methyl hemiacetal, an acetone acetal and an SEM ester). 1716: 1707: 1637: 1601: 521: 453:

The rare double-layer protecting group is a protected protecting group, which exemplify high stability.

232: 4831: 3361:

T. Tsunoda, M. Suzuki, R. Noyori: "A facile procedure for acetalization under aprotic conditions", in:

862: 815:

in methanol, palladium on activated carbon, or diverse platinum complexes – conjoined with acid workup.

384:

Only a few protecting groups can be detached oxidatively: the methoxybenzyl ethers, which oxidize to a

4753: 4559:

Synthetic studies of marine alkaloids hapalindoles. Part 3 Total synthesis of (±)-hapalindoles H and U

4507:

Synthetic studies of marine alkaloids hapalindoles. Part I Total synthesis of (±)-hapalindoles J and M

2823:

Elias J. Corey, Mark G. Bock: "Protection of primary hydroxyl groups as methylthiomethyl ethers", in:

1932:

The exchange of a protecting group from a methyl ether to a MOM-ether inhibits here the opening of an

1804: 858: 4719: 4465: 4383:

K.M. Nicholas, R. Pettit: "On the stability of α-(alkynyl)dicobalt hexacarbonyl carbonium ions", in:

4371: 4348: 4321: 4294: 4089: 4062: 3888: 3807: 3673: 3430: 3376: 3132: 2946: 2919: 2838: 2520: 2493: 2443: 1790: 1644: 1529: 1236: 1209: 1167: 752: 4810: 501: 497: 4398: 4385: 4335: 4124: 3902: 3700: 3063: 2850:

Elias J. Corey, Duy H. Hua, Bai Chuan Pan, Steven P. Seitz: "Total synthesis of aplasmomycin", in:

2724: 2347:

Kyriacos C. Nicolaou, R. A. Daines, T. K. Chakraborty: "Total synthesis of amphoteronolide B", in:

2106: 1746: 1296: 1190: 1182: 1021: 928:. These characteristics imply that new protecting groups for amines are always under development. 728: 594: 363: 95: 72: 528:

byproduct. The trimethylsilyl ethers are also extremely sensitive to acid hydrolysis (for example

4489: 4252:

Wenzel E. Davidsohn, Malcolm C. Henry: "Organometallic Acetylenes of the Main Groups III–V", in:

4229: 4218: 2183: 1918: 1861: 1505: 1311: 586: 3329:

Moussa, Ziad; D. Romo (2006). "Mild deprotection of primary N-(p-toluenesufonyl) amides with SmI

2077:

Michael Schelhaas, Herbert Waldmann: "Schutzgruppenstrategien in der organischen Synthese", in:

2008:

Michael Schelhaas, Herbert Waldmann: "Schutzgruppenstrategien in der organischen Synthese", in:

957:, which admit reductive cleavage, and the trifluoroacetamides, which hydrolyze easily in base. 950:-butoxycarbonyl, benzoxycarbonyl, fluorenylmethylenoxycarbonyl, and allyloxycarbonyl compounds. 4628:, 4th Ed., John Wiley & Sons Inc., Hoboken, New Jersey, pp. 10–13; ISBN 0-471-69754-0. 1856:

An important example of industrial applications of protecting group theory is the synthesis of

1178: 4758: 4639: 4481: 4436: 4362: 4308: 4233: 4049: 3926: 3875: 3848: 3846:

Elias J. Corey, Kyriacos C. Nicolaou, Takeshi Toru: "Total synthesis of (±)-vermiculine", in:

3821: 3794: 3714: 3660: 3633: 3538: 3510: 3417: 3363: 3226: 3172: 3119: 3014: 2933: 2906: 2879: 2852: 2825: 2798: 2743: 2641: 2614: 2560: 2507: 2430: 2377: 2349: 2267: 2206: 2152: 2079: 2045: 2010: 1989: 1944: 1818: 1697: 1651: 1542: 1509: 1452:– Removed by acid. Normally, the cleavage of acyclic acetals is easier than of cyclic acetals. 1144:(trichloroethyl chloroformate ) group – Removed by Zn insertion in the presence of acetic acid 1060: 917: 734: 713: 685:‑Dimethoxybenzyl ether — Removed via oxidation with DDQ or ceric ammonium chloride 611: 532:

suffices as a proton donator) and are consequently rarely used nowadays as protecting groups.

406: 2192: 1715:

In order to protect the triple bond itself, sometimes a transition metal-alkyne complex with

4735: 4674: 4586: 4569: 4543: 4517: 4473: 4456: 4428: 3934: 3605: 3578: 3344: 2680: 2324:

methyl ester involving a new method for the cleavage of a dimethyl-t-butylsilyl ether", in:

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is a common cosolvent, used to promote dissolution. For a non-acidic cleavage technique, a

1015: 798: 635:

Triisopropylsilyl (TIPS) ethers) — Similar conditions to TBS but longer reaction times.

367: 353: 320: 136: 79: 68: 64: 4771: 4599: 4584:

T. Reichstein, A. Grüssner: "Eine ergiebige Synthese der L-Ascorbinsäure (C-Vitamin)", in:

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are the esters of various alcohols. Occasionally, esters are protected as ortho-esters or

32: 1478: 1292: 854: 825: 693: 607: 128: 36: 4469: 1867: 345:

Various groups are cleaved in acid or base conditions, but the others are more unusual.

2685: 2668: 2104:

V.N. Rajasekharan Pillai: "Photoremovable Protecting Groups in Organic Synthesis", in:

1786: 1782: 1578: 1425:

For aldehydes, a temporary protection of the carbonyl group the presence of ketones as

1226: 1216: 1204: 1028: 1003: 943: 756: 653: 582: 475: 335: 281: 252:

Schematic diagram of a solid-state peptide synthesis with orthogonal protecting groups

206: 194: 167: 4573: 4547: 4521: 4412: 1883:

and then deprotected after the oxidation of the primary alcohols to carboxylic acids.

606: — 10–100× stabler than a TMS group. Cleaved with trifluoroacetic acid in water/ 4852: 4825: 4678: 4022: 3995: 3741: 3444: 3199: 2960: 2771: 2587: 2295: 2233: 1895: 1857: 1767: 1743: 1621: 1075: 999: 559: 493: 417: 374: 148: 2669:"Metabolism of 3,4-dimethoxycinnamyl alcohol and derivatives by Coriolus versicolor" 1349:-acetals also have an application, albeit scant, as carbonyl protecting groups too. 762:

Tris(isopropyl)silyloxymethyl (TOM) — Commonly protects 2'-hydroxy function in

446: 4615:, VCH Verlagsgesellschaft mbH, Weinheim 1996, pp. 711–729, ISBN 3-527-29284-5. 4493: 2710: 2335: 1693: 1617: 1432: 850: 722: 621: 385: 378: 277: 4805: 4652: 4267: 4008: 3939: 3921: 3861: 3834: 3754: 3727: 3646: 3551: 3523: 3457: 3403: 3239: 3212: 3185: 3088: 3027: 2973: 2892: 2865: 2811: 2784: 2756: 2654: 2627: 2600: 2573: 2390: 2362: 2308: 2280: 2246: 2219: 2165: 4706: 4281: 4076: 3687: 3390: 3050: 2480: 2262: 1924: 1914: 1850: 1584: 1549: 1135: 954: 931: 925: 921: 804: 794: 748: 671:(PMB) — Removed by acid, hydrogenolysis, or oxidation – commonly with 590: 478: 471: 436: 421: 413: 302: 186: 152: 120: 4749:, 4th Ed., John Wiley & Sons Inc., Hoboken, New Jersey, ISBN 0-471-69754-0. 1624:

or catalytic hydration. For alkenes two protecting groups are basically known:

1414:-Acetals are hydrolyzed a factor of 10,000 times faster than the corresponding 1275: 516:

Trimethylsilyl chloride, activated with imidazole, protects a secondary alcohol

399: 4420: 4254: 4166: 4138: 3968: 1822: 1785:. Crucially, added complexity impedes the use of synthetic total synthesis in 1535: 1459: 1426: 1354: 1315: 1283: 1186: 1071: 1056: 529: 520:

Triorganosilyl sources have quite variable prices, and the most economical is

425: 132: 4820: 4778: 4179: 4151: 4035: 3981: 1891: 1839: 1590: 1520:‑dimethylformamide, or methanol and catalytic trimethylsilyl chloride 1482: 1011: 993: 966: 939: 935: 665: 512: 326: 17: 4792: 4485: 4440: 4413:"Isotope Effects in Photochemistry: Application to Chromatic Orthogonality" 4203: 2612:

Masahiro Hirama, Mitsuko Uei: "A chiral total synthesis of compactin", in:

1798:

Protected and unprotected syntheses of the marine alkaloid, hapalindole U.

731:(MOM) — Removed by 6 M hydrochloric acid in tetrahydrofuran/water 712:

Ethoxyethyl ethers (EE) – Cleavage more trivial than simple ethers e.g. 1N

4568:, Pages 6351–6360 Hideaki Muratake, Harumi Kumagami and Mitsutaka Natsume 3348: 1962: 4216:

Clayden, Jonathan; Greeves, Nick; Warren, Stuart; Wothers, Peter (2000).

3712:

John E. McMurry, Stephen J. Isser: "Total synthesis of longifolene", in:

1937: 1553: 1465: 1123: 1040:(Boc) group — Removed by concentrated strong acid (such as HCl or CF 1007: 598: 571: 308: 217: 99: 27:

Group of atoms introduced into a compound to prevent subsequent reactions

4477: 973:‑sulfonylamides,which are far too stable with aliphatic amines. 3335: 1933: 1880: 1541:

esters – Also removed by acid and some reductants. Can be formed from

1303: 1163: 1131: 1127: 1109: 962: 899: 868: 565: 429: 349: 124: 4432: 1905: 1758: 538: 445: 405: 398: 276:

A further important example of orthogonal protecting groups occurs in

135:– may require protecting groups to order their assembly. Also, cheap 3920:

Romanski, J.; Nowak, P.; Kosinski, K.; Jurczak, J. (September 2012).

1671: 1523: 1501: 1498: 1455: 1445: 1374: 1200: 1159: 1099: 1088: 958: 846: 842: 838: 659: 649: 555: 482: 359: 314: 171:

Orthogonal protection of L-Tyrosine (Protecting groups are marked in

104: 44: 40: 4811:

Senior undergraduate study notes on this subject, from Prof. Rizzo.

271:

Fmoc solid state peptide synthesis with orthogonal protecting groups

4742:, 1st ed., Georg Thieme Verlag, Stuttgart 1994, ISBN 3-13-135601-4. 1087:

group — Removed with complexes of metals like palladium(0) or

539: 492:

The most important esters with common protecting-group use are the

4306:

Kenneth M. Nicholas, R. Pettit: "An alkyne protection group", in:

3270:(PDF; 663 kB) In: Michael W. Pennington, Ben M. Dunn (eds.): 1961: 1923: 1904: 1866: 1817: 1809: 1803: 1574: 1449: 1350: 1282: 1274: 1174: 1147: 812: 511: 486: 467: 332:

Protecting groups cleaved by heavy metal salts or their complexes.

228:-butyl ether cleaved with acids (e.g. with trifluoroacetic acid). 166: 107:, which does not react with hydrides. The acetal is then called a 91: 48: 31: 3922:"High-pressure transesterification of sterically hindered esters" 1886:

A very spectacular example application of protecting groups from

1664:

2-cyanoethyl – removed by mild base. The group is widely used in

71:

in a subsequent chemical reaction. It plays an important role in

2585:

W. Clark Still, Dominick Mobilio: "Synthesis of asperdiol", in:

1719:

is used. The release of the cobalt then follows from oxidation.

1633: 1052: 296: 845:, in that one protects both hydroxy groups codependently as an 721:(MEM) — Removed by hydrobromic acid in tetrahydrofuran or 662:(triphenylmethyl, Tr) — Removed by acid and hydrogenolysis 4806:

Introduction of protecting group and mechanism of deprotection

969: — verily any aza-heterocycle — admit protection as 737:(THP) — Removed by acetic acid in tetrahydrofuran/water, 4756:: "Schutzgruppenstrategien in der organischen Synthese", in: 1875:

In order to prevent oxidation of the secondary alcohols with

4695:. Reprint 2004, Oxford University Press, ISBN 0-19-963724-5. 1721: 1706: 1650: 1431: 881: 867: 656:. Bn group is widely used in sugar and nucleoside chemistry. 63:

is introduced into a molecule by chemical modification of a

3770:, Ferdinand Enke Verlag, Stuttgart 1965, pp. 127–133. 1568:-catalyzed high-pressure methanolysis at room temperature. 703:

Methoxytrityl (MMT) – Removed by acid and hydrogenolysis.

568:(Bz) – Removed by acid or base, more stable than Ac group. 4613:

Classics in Total Synthesis: Targets, Strategies, Methods

4542:, Pages 6343–6350 Hideaki Muratake and Mitsutaka Natsume 4516:, Pages 6331–6342 Hideaki Muratake and Mitsutaka Natsume 2261:

James D. White, Motoji Kawasaki: "Total synthesis of (+)-

3274:

volume 35, 1995, ISBN 978-0-89603-273-6, pp. 17–27.

485:, deprotected by weak acids. In rarer cases, a carbon 1138:. Too stable to readily remove from aliphatic amides. 1825:'s protecting-group free synthesis, reported in 2007. 1508:. Can be formed from diazomethane in diethyl ether, 1055:) group — Removed by base, such as 20–50 % 797:(tBu) – Removed with anhydrous trifluoroacetic acid, 1763:

Orthogonal protection Application in Photochemistry

1044:COOH), or by heating to >80 °C. Common in 508:

Chloroacetyl > acetyl > benzoyl > pivaloyl

90:is a highly reactive reagent that usefully reduces 4217: 3115:An Exceptionally Mild Deprotection of Phthalimides 2257: 2255: 1587:– Converted to standard ester by mild aqueous acid 1545:: isobutene in dioxane and catalytic sulfuric acid 1532:esters — Same as benzyl, but easier to cleave 791:-Methoxyphenyl ether (PMP) – Removed by oxidation. 628:in THF. Commonly protects 2'-hydroxy function in 1150:(Ts) group – Removed by concentrated acid (HBr, H 977:‑benzylated amines can be removed through 466:The classical protecting groups for alcohols are 4842:Schutzgruppen in der organischen Synthesechemie 3291:volume 109, 1997, pp. 629–631 (in German). 4747:Green's Protective Groups in Organic Synthesis 4626:Green's Protective Groups in Organic Synthesis 4411:Blanc, Aurélien; Bochet, Christian G. (2007). 3113:John O. Osby, Michael G. Martin, Bruce Ganem: 481:, deprotected by acids and fluoride ions; and 381:: ethers, esters, urethanes, carbonates, etc. 51:reduction, vs. unprotected reduction to a diol 1984:Theodora W. Greene; Peter G. M. Wuts (1999). 1742:orthogonal deprotection is demonstrated in a 1526:esters — Also removed by hydrogenolysis. 1468:– Removed by metal salts or oxidizing agents. 1388:-acetals normally follows analogously to the 1130:. Removed by base, often aqueous or gaseous 801:in acetic acid, or 4 N hydrochloric acid 8: 1318:can be performed with workup in chloroform. 953:Other, more exotic amine protectors are the 237: 1871:The Reichstein synthesis (of ascorbic acid) 942:. When a carbamate deprotects, it evolves 610:, acetic acid in water/tetrahydrofuran, or 2293:3'-deuterioadenosine from adenosine", in: 1879:, they are protected via acetalation with 624:, pyridinium fluoride in tetrahydrofuran, 3938: 2684: 1628:Temporary halogenation with bromine to a 1477:The most important protecting groups for 1018:, or lithium or sodium in liquid ammonia. 996:group – Removed by acid and mild heating. 946:. The commonest-used carbamates are the 4777:Krzysztof Jarowicki, Philip Kocieński: " 1808:Hideaki Muratake's 1990 synthesis using 893: 741:‑toluenesulfonic acid in methanol 443:-nitrobenzylgroup ought be listed here. 432:(resp. amine) hydrolyzes in light acid. 348:Fluoride ions form very strong bonds to 2036:Chan, Weng C.; White, Peter D. (2004). 1976: 242: 1986:Protecting Groups in Organic Synthesis 1674:(Me) – removed by strong nucleophiles 4745:Peter G.M. Wuts, Theodora W. Greene: 4624:Peter G.M. Wuts, Theodora W. Greene: 1189:or other soft thiol nucleophiles, or 770:β‑(Trimethylsilyl)ethoxymethyl 435:Photolabile protecting groups bear a 7: 3267:Methods for Removing the Fmoc Group. 916:Amines have a special importance in 558:(Ac) – Removed by acid or base (see 420:to a vinyl group in the presence of 3303:Fmoc Solid Phase Peptide Synthesis. 2667:Kamaya, Yasushi; T Higuchi (2006). 1966:Automatic oligonucleotide synthesis 1606:Grignard (organomagnesium) reagents 1310:acetonitrile complex in acetone or 849:. Common in this situation are the 778:Hexamethyl phosphoric acid triamide 362:and other enzymes cleave ethers at 4693:Fmoc Solid Phase Peptide Synthesis 3253:Fmoc Solid Phase Peptide Synthesis 2686:10.1111/j.1574-6968.1984.tb01309.x 2066:Fmoc Solid Phase Peptide Synthesis 2038:Fmoc Solid Phase Peptide Synthesis 1812:protecting groups (shown in blue). 1577:esters – Also removed by base and 906:-butyloxycarbonyl group is marked 25: 4720:doi:10.1016/S0040-4020(01)88752-4 4372:doi:10.1016/S0040-4039(01)83455-9 4349:doi:10.1016/S0022-328X(00)89454-1 4322:doi:10.1016/S0040-4039(01)97209-0 4295:doi:10.1016/S0040-4020(02)00315-0 4090:doi:10.1016/S0040-4020(97)10203-4 4063:doi:10.1016/S0040-4039(00)97045-X 3889:doi:10.1016/S0040-4039(01)94936-6 3808:doi:10.1016/S0040-4039(00)88171-X 3674:doi:10.1016/S0040-4039(00)92243-3 3431:doi:10.1016/S0040-4039(00)89114-5 3377:doi:10.1016/S0040-4039(00)74575-8 3333:following trifluoroacetylation". 3133:doi:10.1016/S0040-4039(01)81169-2 2947:doi:10.1016/S0040-4039(00)82883-X 2920:doi:10.1016/S0040-4039(00)85501-X 2839:doi:10.1016/S0040-4039(00)91422-9 2521:doi:10.1016/S0040-4039(00)86974-9 2494:doi:10.1016/S0040-4020(01)96051-X 2444:doi:10.1016/S0040-4039(00)84045-9 1683:Terminal alkyne protecting groups 1473:Carboxylic acid protecting groups 1027:(Moz or MeOZ) group – Removed by 78:In many preparations of delicate 4399:doi:10.1016/0022-328X(72)80037-8 4125:doi:10.5012/bkcs.2010.31.10.2757 3701:doi:10.1016/0040-4020(78)80243-9 3064:doi:10.1016/0040-4020(82)80083-5 1548:2,6‑Dialkylphenols (e.g. 1504: — Also removed by acid or 1158:) & strong reducing agents ( 1118:) groups — common in 934:are primarily protected through 341:Double-layered protecting groups 280:chemistry. As carbohydrates or 264: 245: 205:-butyl ether protected phenolic 1890:is the 1994 total synthesis of 807: — Removed with potassium 4784:J. Chem. Soc., Perkin Trans. 1 4691:Weng C. Chan, Peter D. White: 4611:K.C. Nicolaou, E.J. Sorensen: 4195:J. Chem. Soc., Perkin Trans. 1 3251:Weng C. Chan, Peter D. White: 2702:J. Chem. Soc., Perkin Trans. 1 2327:J. Chem. Soc., Perkin Trans. 1 2064:Weng C. Chan, Peter D. White: 1365:-acetals are, unlike the pure 1051:9-Fluorenylmethyloxycarbonyl ( 1002:(Cbz) group — Removed by 751:metal oxidants: base-buffered 428:(from a protected alcohol) or 238:§ Industrial applications 1: 4821:A review by Prof. Kocienski. 4574:10.1016/S0040-4020(01)96007-7 4548:10.1016/S0040-4020(01)96006-5 4522:10.1016/S0040-4020(01)96005-3 2193:doi:10.1002/jlac.198619860714 1853:(Tamiflu, an antiviral drug) 1736:Photolabile protecting groups 1080:solid phase peptide synthesis 1046:solid phase peptide synthesis 177:, the amino acid is shown in 4772:doi:10.1002/ange.19961081805 4679:10.1016/0307-4412(79)90078-5 4600:doi:10.1002/hlca.19340170136 3940:10.1016/j.tetlet.2012.07.094 3619:doi:10.1002/hlca.19860690311 3592:doi:10.1002/hlca.19830660815 2093:doi:10.1002/ange.19961081805 2024:doi:10.1002/ange.19961081805 1377:-protected carbonyl groups. 388:. They can be removed with 3306:retrieved 16 November 2013. 3272:Peptide Synthesis Protocols 1702:tetrabutylammonium fluoride 1659:Phosphate protecting groups 1244:ammonium cerium(IV) nitrate 1181:) groups — Removed by 924:and also relatively strong 877:diisobutyl aluminum hydride 774:tetrabutylammonium fluoride 747: — Removed by acid or 626:tetrabutylammonium fluoride 394:dichlorodicyanobenzoquinone 73:multistep organic synthesis 4880: 3040:derivatives with the LiAlH 2458:Carbonhydr. Chem. Biochem. 1816: 1751:trimethylsilyldiazomethane 1251:Carbonyl protecting groups 377:removes a wide variety of 145:enantioselective synthesis 2673:FEMS Microbiology Letters 1957:oligonucleotide synthesis 1888:natural product synthesis 1666:oligonucleotide synthesis 1564:) — Also removed in 1242:(PMP) group – Removed by 1219:, more labile than benzyl 1120:oligonucleotide synthesis 1025:-Methoxybenzyloxycarbonyl 920:, but are a quite potent 764:oligonucleotide synthesis 719:Methoxyethoxymethyl ether 698:oligonucleotide synthesis 630:oligonucleotide synthesis 462:Alcohol protecting groups 329:-labile protecting groups 323:-labile protecting groups 317:-labile protecting groups 311:-labile protecting groups 305:-labile protecting groups 299:-labile protecting groups 193:) benzyl ester protected 88:lithium aluminium hydride 2711:doi:10.1039/P19810001796 2492:, pp. 10023–10034; 2336:doi:10.1039/P19810002055 1988:(3 ed.). J. Wiley. 1203:(Bn) group – Removed by 828:(THF) – Removed by acid. 457:Common protecting groups 137:chiral protecting groups 98:. It always reacts with 4653:doi:10.1021/ja00067a026 4564:, Volume 46, Issue 18, 4538:, Volume 46, Issue 18, 4512:, Volume 46, Issue 18, 4268:doi:10.1021/cr60245a003 4226:Oxford University Press 4112:Bull. Korean Chem. Soc. 4009:doi:10.1021/jo00926a024 3862:doi:10.1021/ja00841a058 3835:doi:10.1021/ja00235a052 3768:Katalytische Hydrierung 3755:doi:10.1021/jo00356a002 3728:doi:10.1021/ja00775a044 3647:doi:10.1021/ja00160a047 3552:doi:10.1021/ja00010a030 3524:doi:10.1021/ja00228a051 3458:doi:10.1021/jo00353a027 3404:doi:10.1246/cl.1981.375 3240:doi:10.1021/ja00029a031 3213:doi:10.1021/jo00405a045 3186:doi:10.1021/ja00213a031 3089:doi:10.1021/jo00253a020 3028:doi:10.1021/ja00297a038 2974:doi:10.1021/jo00193a051 2893:doi:10.1021/ja00325a032 2866:doi:10.1021/ja00388a074 2812:doi:10.1021/ja00474a058 2785:doi:10.1021/jo01323a017 2757:doi:10.1021/ja00242a053 2655:doi:10.1021/ja00341a055 2628:doi:10.1021/ja00379a037 2601:doi:10.1021/jo00172a070 2574:doi:10.1021/ja00547a037 2391:doi:10.1021/ja00036a045 2363:doi:10.1021/ja00241a063 2309:doi:10.1021/jo00289a004 2281:doi:10.1021/ja00168a071 2247:doi:10.1021/jo00019a004 2220:doi:10.1021/ja00175a038 2166:doi:10.1021/ja00164a023 2042:Oxford University Press 1949:Robert Bruce Merrifield 1834:Industrial applications 1766:Due to this effect the 1690:methylmagnesium bromide 1122:for protection of N in 979:catalytic hydrogenation 890:Amine protecting groups 780:) or in tetrahydrofuran 755:in wet acetonitrile or 652:(Bn) — Removed by 288:Cleavage categorization 4830:Organic-Reaction.com: 4791:, pp. 4005–4037; 4770:, pp. 2192–2219; 4718:, pp. 2223–2311; 4651:, pp. 6094–6100; 4370:, pp. 4163–4166; 4320:, pp. 3475–3478; 4293:, pp. 4133–4170; 4202:, pp. 3555–3558; 4150:, pp. 1163–1190; 4123:, pp. 2757–2758; 4088:, pp. 1021–1028; 4061:, pp. 6291–6293; 4007:, pp. 1426–1427; 3980:, pp. 2035–2052; 3887:, pp. 3051–3054; 3860:, pp. 2287–2288; 3806:, pp. 3573–3576; 3726:, pp. 7132–7137; 3699:, pp. 3269–3274; 3672:, pp. 2565–2566; 3645:, pp. 1607–1617; 3590:, pp. 2501–2511; 3550:, pp. 3850–3866; 3522:, pp. 6890–6891; 3375:, pp. 1357–1358; 3211:, pp. 2285–2286; 3131:, pp. 2093–2096; 3062:, pp. 3721–3727; 3026:, pp. 3279–3285; 2972:, pp. 3671–3672; 2945:, pp. 5417–5418; 2891:, pp. 3869–3870; 2864:, pp. 6818–6820; 2837:, pp. 3269–3270; 2810:, pp. 1942–1943; 2783:, pp. 1438–1447; 2755:, pp. 2523–2525; 2709:, pp. 1796–1801; 2626:, pp. 4251–4253; 2599:, pp. 4785–4786; 2572:, pp. 7962–7965; 2536:‑methoxybenzyl. 2389:, pp. 3910–3926; 2361:, pp. 2208–2210; 2334:, pp. 2055–2058; 2279:, pp. 4991–4993; 2245:, pp. 5496–5498; 2218:, pp. 7001–7031; 2191:, pp. 1281–1308; 2164:, pp. 2998–3017; 2091:, pp. 2195–2200; 1967: 1929: 1910: 1877:potassium permanganate 1872: 1826: 1813: 1764: 1755:kinetic isotope effect 1726: 1712: 1655: 1602:organolithium reagents 1436: 1308:palladium(II) chloride 1288: 1280: 1031:, more labile than Cbz 913: 886: 872: 837:The 1,2‑diols ( 759:in wet tetrahydrofuran 745:Methylthiomethyl ether 543: 517: 450: 410: 403: 390:ceric ammonium nitrate 210: 52: 4667:Biochemical Education 4180:doi:10.1021/ol0070029 4152:doi:10.1021/cr9803840 4036:doi:10.1021/jo9713363 3982:doi:10.1021/cr950083f 3349:10.1055/s-2006-951530 3238:, pp. 998–1010; 3184:, p. 1547–1557; 3087:, pp. 4274–4282 1965: 1927: 1908: 1870: 1821: 1807: 1762: 1725: 1717:dicobalt octacarbonyl 1711:Alkyne TMS protection 1710: 1654: 1643:Protection through a 1638:titanocene dichloride 1554:2,6-diisopropylphenol 1512:and methyl iodide in 1435: 1286: 1278: 1074:in DMF for sensitive 1068:-Methyl-2-pyrrolidone 897: 885: 871: 542: 522:chlorotrimethylsilane 515: 449: 409: 402: 233:solid-phase synthesis 214:Orthogonal protection 170: 163:Orthogonal protection 35: 4793:doi:10.1039/A803688H 4598:, pp. 311–328; 4204:doi:10.1039/b006759h 4178:, pp. 679–681; 4034:, pp. 169–176; 3833:, pp. 287–289; 3753:, pp. 773–784; 3617:, pp. 621–625; 3456:, pp. 404–407; 3429:, pp. 705–708; 3402:, pp. 375–376; 2918:, pp. 445–448; 2653:, pp. 625–627; 2519:, pp. 885–888; 2442:, pp. 579–580; 2307:, pp. 410–412; 1791:biomimetic synthesis 1645:Diels-Alder reaction 1440:Types of protectants 1287:1,3‑Propadiol 1225:(DMPM) – Removed by 1168:sodium naphthalenide 669:-Methoxybenzyl ether 614:in water or pyridine 4837:Universität Marburg 4752:Michael Schelhaas, 4736:Philip J. Kocieński 4478:10.1038/nature05569 4470:2007Natur.446..404B 4386:J. Organomet. Chem. 4336:J. Organomet. Chem. 4266:, pp. 73–106; 3957:, pp. 139–142. 3499:, pp. 178–180. 3319:, pp. 199–201. 3283:B. Liebe, H. Kunz: 3148:, pp. 220–227. 2732:, pp. 276–277. 2532:See literature for 1842:(sweetener) or the 1799: 1747:transesterification 1696:in tetrahydrofuran/ 1229:, more labile than 1223:3,4-Dimethoxybenzyl 1215:(PMB) – Removed by 1191:tributyltin hydride 1173:Other sulfonamide ( 729:Methoxymethyl ether 595:potassium carbonate 4859:Chemical synthesis 3766:F. Zymalkokowski: 3473:, S. 167–170. 2184:Liebigs Ann. Chem. 1968: 1930: 1911: 1873: 1827: 1814: 1797: 1765: 1727: 1713: 1678:. thiophenole/TEA. 1656: 1550:2,6-dimethylphenol 1506:pig liver esterase 1437: 1312:iron(III) chloride 1289: 1281: 914: 887: 873: 725:in dichloromethane 587:Potassium fluoride 544: 518: 451: 411: 404: 211: 53: 4864:Protecting groups 4779:Protecting groups 4759:Angewandte Chemie 4740:Protecting Groups 4640:J. Am. Chem. Soc. 4464:(7134): 404–408. 4433:10.1021/ol070820h 4427:(14): 2649–2651. 4363:Tetrahedron Lett. 4309:Tetrahedron Lett. 4239:978-0-19-850346-0 4220:Organic Chemistry 4109:/Ga System", in: 4050:Tetrahedron Lett. 3955:Protecting Groups 3933:(39): 5287–5289. 3927:Tetrahedron Lett. 3910:, pp. 63–64. 3876:Tetrahedron Lett. 3849:J. Am. Chem. Soc. 3822:J. Am. Chem. Soc. 3795:Tetrahedron Lett. 3781:Protecting Groups 3715:J. Am. Chem. Soc. 3661:Tetrahedron Lett. 3634:J. Am. Chem. Soc. 3565:Protecting Groups 3539:J. Am. Chem. Soc. 3511:J. Am. Chem. Soc. 3497:Protecting Groups 3484:Protecting Groups 3471:Protecting Groups 3418:Tetrahedron Lett. 3364:Tetrahedron Lett. 3343:(19): 3294–3298. 3317:Protecting Groups 3264:Gregg B. Fields: 3255:, pp. 27–30. 3227:J. Am. Chem. Soc. 3173:J. Am. Chem. Soc. 3159:Protecting Groups 3146:Protecting Groups 3120:Tetrahedron Lett. 3102:Protecting Groups 3015:J. Am. Chem. Soc. 3000:Protecting Groups 2989:, pp. 59–60. 2987:Protecting Groups 2934:Tetrahedron Lett. 2907:Tetrahedron Lett. 2880:J. Am. Chem. Soc. 2853:J. Am. Chem. Soc. 2826:Tetrahedron Lett. 2799:J. Am. Chem. Soc. 2744:J. Am. Chem. Soc. 2642:J. Am. Chem. Soc. 2615:J. Am. Chem. Soc. 2561:J. Am. Chem. Soc. 2547:Protecting Groups 2508:Tetrahedron Lett. 2431:Tetrahedron Lett. 2419:, pp. 46–49. 2417:Protecting Groups 2404:Protecting Groups 2378:J. Am. Chem. Soc. 2350:J. Am. Chem. Soc. 2268:J. Am. Chem. Soc. 2207:J. Am. Chem. Soc. 2153:J. Am. Chem. Soc. 2138:Protecting Groups 2125:Protecting Groups 2080:Angewandte Chemie 2051:978-0-19-963724-9 2022:, pp. 2194; 2011:Angewandte Chemie 1995:978-0-471-16019-9 1945:peptide synthesis 1860:(Vitamin C) à la 1831: 1830: 1698:dimethylsulfoxide 1543:carboalkoxylation 1510:caesium carbonate 1493:Protecting groups 1380:The formation of 1085:Allyloxycarbamate 1061:dimethylformamide 1038:-Butyloxycarbonyl 938:, typically as a 918:peptide synthesis 811:‑butoxide 795:Tert-butyl ethers 753:mercuric chloride 735:Tetrahydropyranyl 714:hydrochloric acid 612:hydrogen fluoride 470:, deprotected by 338:protecting groups 185:) Fmoc-protected 80:organic compounds 16:(Redirected from 4871: 4832:Protecting Group 4754:Herbert Waldmann 4723: 4702: 4696: 4689: 4683: 4682: 4662: 4656: 4635: 4629: 4622: 4616: 4609: 4603: 4587:Helv. Chim. Acta 4582: 4576: 4556: 4550: 4530: 4524: 4504: 4498: 4497: 4451: 4445: 4444: 4417: 4408: 4402: 4381: 4375: 4358: 4352: 4331: 4325: 4304: 4298: 4277: 4271: 4250: 4244: 4243: 4223: 4213: 4207: 4189: 4183: 4161: 4155: 4134: 4128: 4099: 4093: 4072: 4066: 4045: 4039: 4018: 4012: 3991: 3985: 3964: 3958: 3953:P.J. Kocieński: 3951: 3945: 3944: 3942: 3917: 3911: 3898: 3892: 3871: 3865: 3844: 3838: 3817: 3811: 3790: 3784: 3779:P.J. Kocieński: 3777: 3771: 3764: 3758: 3737: 3731: 3710: 3704: 3683: 3677: 3656: 3650: 3628: 3622: 3606:Helv. Chim. Acta 3601: 3595: 3579:Helv. Chim. Acta 3574: 3568: 3563:P.J. Kocieński: 3561: 3555: 3533: 3527: 3506: 3500: 3495:P.J. Kocieński: 3493: 3487: 3482:P.J. Kocieński: 3480: 3474: 3469:P.J. Kocieński: 3467: 3461: 3440: 3434: 3413: 3407: 3386: 3380: 3359: 3353: 3352: 3326: 3320: 3315:P.J. Kocieński: 3313: 3307: 3298: 3292: 3281: 3275: 3262: 3256: 3249: 3243: 3222: 3216: 3195: 3189: 3168: 3162: 3157:P.J. Kocieński: 3155: 3149: 3144:P.J. Kocieński: 3142: 3136: 3111: 3105: 3100:P.J. Kocieński: 3098: 3092: 3073: 3067: 3037: 3031: 3009: 3003: 2998:P.J. Kocieński: 2996: 2990: 2985:P.J. Kocieński: 2983: 2977: 2956: 2950: 2929: 2923: 2902: 2896: 2875: 2869: 2848: 2842: 2821: 2815: 2794: 2788: 2766: 2760: 2739: 2733: 2720: 2714: 2697: 2691: 2690: 2688: 2679:(2–3): 225–229. 2664: 2658: 2637: 2631: 2610: 2604: 2583: 2577: 2556: 2550: 2545:P.J. Kocieński: 2543: 2537: 2530: 2524: 2503: 2497: 2476: 2470: 2453: 2447: 2426: 2420: 2415:P.J. Kocieński: 2413: 2407: 2402:P.J. Kocieński: 2400: 2394: 2372: 2366: 2345: 2339: 2318: 2312: 2290: 2284: 2259: 2250: 2229: 2223: 2202: 2196: 2180: 2175: 2169: 2147: 2141: 2136:P.J. Kocieński: 2134: 2128: 2123:P.J. Kocieński: 2121: 2115: 2114:, pp. 1–26. 2102: 2096: 2075: 2069: 2068:, S. 10–12. 2062: 2056: 2055: 2033: 2027: 2006: 2000: 1999: 1981: 1800: 1796: 1740:proof of concept 1479:carboxylic acids 1117: 1116: 1107: 1106: 1016:activated carbon 911: 863:cyclopentylidene 799:hydrogen bromide 424:. The residual 354:steric hindrance 268: 249: 176: 129:oligosaccharides 109:protecting group 69:chemoselectivity 65:functional group 61:protective group 57:protecting group 21: 4879: 4878: 4874: 4873: 4872: 4870: 4869: 4868: 4849: 4848: 4802: 4732: 4730:Further reading 4727: 4726: 4703: 4699: 4690: 4686: 4664: 4663: 4659: 4636: 4632: 4623: 4619: 4610: 4606: 4583: 4579: 4557: 4553: 4531: 4527: 4505: 4501: 4453: 4452: 4448: 4415: 4410: 4409: 4405: 4382: 4378: 4359: 4355: 4332: 4328: 4305: 4301: 4278: 4274: 4251: 4247: 4240: 4215: 4214: 4210: 4190: 4186: 4162: 4158: 4135: 4131: 4108: 4104: 4100: 4096: 4073: 4069: 4046: 4042: 4019: 4015: 3992: 3988: 3965: 3961: 3952: 3948: 3919: 3918: 3914: 3899: 3895: 3872: 3868: 3845: 3841: 3818: 3814: 3791: 3787: 3783:, pp. 136. 3778: 3774: 3765: 3761: 3738: 3734: 3711: 3707: 3684: 3680: 3657: 3653: 3629: 3625: 3602: 3598: 3575: 3571: 3567:, pp. 119. 3562: 3558: 3534: 3530: 3507: 3503: 3494: 3490: 3486:, pp. 176. 3481: 3477: 3468: 3464: 3441: 3437: 3414: 3410: 3387: 3383: 3360: 3356: 3332: 3328: 3327: 3323: 3314: 3310: 3299: 3295: 3282: 3278: 3263: 3259: 3250: 3246: 3223: 3219: 3196: 3192: 3169: 3165: 3156: 3152: 3143: 3139: 3112: 3108: 3099: 3095: 3074: 3070: 3047: 3043: 3038: 3034: 3010: 3006: 2997: 2993: 2984: 2980: 2957: 2953: 2930: 2926: 2903: 2899: 2876: 2872: 2849: 2845: 2822: 2818: 2795: 2791: 2767: 2763: 2740: 2736: 2721: 2717: 2698: 2694: 2666: 2665: 2661: 2638: 2634: 2611: 2607: 2584: 2580: 2557: 2553: 2544: 2540: 2531: 2527: 2504: 2500: 2477: 2473: 2454: 2450: 2427: 2423: 2414: 2410: 2401: 2397: 2373: 2369: 2346: 2342: 2323: 2319: 2315: 2291: 2287: 2260: 2253: 2230: 2226: 2203: 2199: 2178: 2176: 2172: 2148: 2144: 2135: 2131: 2122: 2118: 2103: 2099: 2076: 2072: 2063: 2059: 2052: 2035: 2034: 2030: 2007: 2003: 1996: 1983: 1982: 1978: 1973: 1836: 1778: 1732: 1685: 1661: 1614: 1598: 1495: 1475: 1442: 1293:ethylene glycol 1279:Ethylene glycol 1253: 1183:samarium iodide 1157: 1153: 1114: 1113: 1104: 1103: 1043: 987: 907: 892: 859:cyclohexylidene 835: 826:Tetrahydrofuran 821: 707:Benzyloxymethyl 694:Dimethoxytrityl 645:Benzyl ethers: 608:tetrahydrofuran 549: 502:pivalate esters 489:might be used. 464: 459: 414:Allyl compounds 290: 282:hydroxyl groups 272: 269: 260: 250: 172: 165: 86:. For example, 37:Ethylene glycol 28: 23: 22: 15: 12: 11: 5: 4877: 4875: 4867: 4866: 4861: 4851: 4850: 4847: 4846: 4834: 4828: 4823: 4818: 4813: 4808: 4801: 4800:External links 4798: 4797: 4796: 4775: 4750: 4743: 4731: 4728: 4725: 4724: 4697: 4684: 4657: 4630: 4617: 4604: 4577: 4551: 4525: 4499: 4446: 4403: 4376: 4353: 4326: 4299: 4272: 4245: 4238: 4208: 4184: 4156: 4129: 4106: 4102: 4094: 4067: 4040: 4013: 3986: 3959: 3946: 3912: 3893: 3866: 3839: 3812: 3785: 3772: 3759: 3732: 3705: 3678: 3651: 3623: 3596: 3569: 3556: 3528: 3501: 3488: 3475: 3462: 3435: 3408: 3381: 3354: 3330: 3321: 3308: 3300:ChemPep Inc.: 3293: 3276: 3257: 3244: 3217: 3190: 3163: 3161:, p. 195. 3150: 3137: 3106: 3104:, p. 186. 3093: 3068: 3048:reagent", in: 3045: 3041: 3032: 3004: 2991: 2978: 2951: 2924: 2897: 2870: 2843: 2816: 2789: 2761: 2734: 2715: 2692: 2659: 2632: 2605: 2578: 2551: 2538: 2525: 2498: 2471: 2469:, pp. 79. 2455:B. Helferich: 2448: 2421: 2408: 2395: 2367: 2340: 2321: 2313: 2285: 2251: 2224: 2197: 2170: 2142: 2129: 2116: 2097: 2070: 2057: 2050: 2028: 2001: 1994: 1975: 1974: 1972: 1969: 1835: 1832: 1829: 1828: 1815: 1789:. In contrast 1787:drug discovery 1783:chemical yield 1777: 1774: 1773: 1772: 1753:utilizing the 1731: 1728: 1684: 1681: 1680: 1679: 1669: 1660: 1657: 1649: 1648: 1641: 1613: 1610: 1609: 1608: 1596: 1588: 1582: 1579:organometallic 1572: 1569: 1546: 1533: 1527: 1521: 1494: 1491: 1474: 1471: 1470: 1469: 1463: 1453: 1441: 1438: 1357:and the mixed 1333:-acetals, the 1252: 1249: 1248: 1247: 1240:-Methoxyphenyl 1234: 1233:-methoxybenzyl 1227:hydrogenolysis 1220: 1217:hydrogenolysis 1213:-Methoxybenzyl 1207: 1205:hydrogenolysis 1196:Benzylamines: 1194: 1193: 1171: 1155: 1151: 1145: 1139: 1095:Other amides: 1093: 1092: 1082: 1049: 1041: 1032: 1029:hydrogenolysis 1019: 1004:hydrogenolysis 1000:Carbobenzyloxy 997: 986: 983: 944:carbon dioxide 891: 888: 855:isopropylidene 834: 831: 830: 829: 823: 819: 816: 802: 792: 784:Other ethers: 782: 781: 767: 760: 757:silver nitrate 742: 732: 726: 716: 710: 704: 701: 687: 686: 676: 663: 657: 654:hydrogenolysis 643: 642: 636: 633: 615: 601: 583:Trimethylsilyl 578:Silyl ethers: 576: 575: 569: 563: 548: 545: 526:Direct Process 510: 509: 476:triorganosilyl 463: 460: 458: 455: 343: 342: 339: 333: 330: 324: 318: 312: 306: 300: 289: 286: 274: 273: 270: 263: 261: 251: 244: 207:hydroxyl group 195:carboxyl group 164: 161: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 4876: 4865: 4862: 4860: 4857: 4856: 4854: 4844: 4843: 4838: 4835: 4833: 4829: 4827: 4824: 4822: 4819: 4817: 4814: 4812: 4809: 4807: 4804: 4803: 4799: 4794: 4790: 4786: 4785: 4780: 4776: 4773: 4769: 4765: 4761: 4760: 4755: 4751: 4748: 4744: 4741: 4737: 4734: 4733: 4729: 4721: 4717: 4713: 4709: 4708: 4701: 4698: 4694: 4688: 4685: 4680: 4676: 4672: 4668: 4661: 4658: 4654: 4650: 4646: 4642: 4641: 4634: 4631: 4627: 4621: 4618: 4614: 4608: 4605: 4601: 4597: 4593: 4589: 4588: 4581: 4578: 4575: 4571: 4567: 4563: 4560: 4555: 4552: 4549: 4545: 4541: 4537: 4534: 4529: 4526: 4523: 4519: 4515: 4511: 4508: 4503: 4500: 4495: 4491: 4487: 4483: 4479: 4475: 4471: 4467: 4463: 4459: 4458: 4450: 4447: 4442: 4438: 4434: 4430: 4426: 4423: 4422: 4414: 4407: 4404: 4400: 4396: 4392: 4388: 4387: 4380: 4377: 4373: 4369: 4365: 4364: 4357: 4354: 4350: 4346: 4342: 4338: 4337: 4330: 4327: 4323: 4319: 4315: 4311: 4310: 4303: 4300: 4296: 4292: 4288: 4284: 4283: 4276: 4273: 4269: 4265: 4261: 4257: 4256: 4249: 4246: 4241: 4235: 4231: 4227: 4222: 4221: 4212: 4209: 4205: 4201: 4197: 4196: 4188: 4185: 4181: 4177: 4173: 4169: 4168: 4160: 4157: 4153: 4149: 4145: 4141: 4140: 4133: 4130: 4126: 4122: 4118: 4114: 4113: 4098: 4095: 4091: 4087: 4083: 4079: 4078: 4071: 4068: 4064: 4060: 4056: 4052: 4051: 4044: 4041: 4037: 4033: 4029: 4025: 4024: 4023:J. Org. Chem. 4017: 4014: 4010: 4006: 4002: 3998: 3997: 3996:J. Org. Chem. 3990: 3987: 3983: 3979: 3975: 3971: 3970: 3963: 3960: 3956: 3950: 3947: 3941: 3936: 3932: 3929: 3928: 3923: 3916: 3913: 3909: 3905: 3904: 3897: 3894: 3890: 3886: 3882: 3878: 3877: 3870: 3867: 3863: 3859: 3855: 3851: 3850: 3843: 3840: 3836: 3832: 3828: 3824: 3823: 3816: 3813: 3809: 3805: 3801: 3797: 3796: 3789: 3786: 3782: 3776: 3773: 3769: 3763: 3760: 3756: 3752: 3748: 3744: 3743: 3742:J. Org. Chem. 3736: 3733: 3729: 3725: 3721: 3717: 3716: 3709: 3706: 3702: 3698: 3694: 3690: 3689: 3682: 3679: 3675: 3671: 3667: 3663: 3662: 3655: 3652: 3648: 3644: 3640: 3636: 3635: 3627: 3624: 3620: 3616: 3612: 3608: 3607: 3600: 3597: 3593: 3589: 3585: 3581: 3580: 3573: 3570: 3566: 3560: 3557: 3553: 3549: 3545: 3541: 3540: 3532: 3529: 3525: 3521: 3517: 3513: 3512: 3505: 3502: 3498: 3492: 3489: 3485: 3479: 3476: 3472: 3466: 3463: 3459: 3455: 3451: 3447: 3446: 3445:J. Org. Chem. 3439: 3436: 3432: 3428: 3424: 3420: 3419: 3412: 3409: 3405: 3401: 3397: 3393: 3392: 3385: 3382: 3378: 3374: 3370: 3366: 3365: 3358: 3355: 3350: 3346: 3342: 3338: 3337: 3325: 3322: 3318: 3312: 3309: 3305: 3304: 3297: 3294: 3290: 3286: 3280: 3277: 3273: 3269: 3268: 3261: 3258: 3254: 3248: 3245: 3241: 3237: 3233: 3229: 3228: 3221: 3218: 3214: 3210: 3206: 3202: 3201: 3200:J. Org. Chem. 3194: 3191: 3187: 3183: 3179: 3175: 3174: 3167: 3164: 3160: 3154: 3151: 3147: 3141: 3138: 3134: 3130: 3126: 3122: 3121: 3116: 3110: 3107: 3103: 3097: 3094: 3090: 3086: 3082: 3078: 3077:J. Org. Chem. 3072: 3069: 3065: 3061: 3057: 3053: 3052: 3036: 3033: 3029: 3025: 3021: 3017: 3016: 3008: 3005: 3002:, p. 62. 3001: 2995: 2992: 2988: 2982: 2979: 2975: 2971: 2967: 2963: 2962: 2961:J. Org. Chem. 2955: 2952: 2948: 2944: 2940: 2936: 2935: 2928: 2925: 2921: 2917: 2913: 2909: 2908: 2901: 2898: 2894: 2890: 2886: 2882: 2881: 2874: 2871: 2867: 2863: 2859: 2855: 2854: 2847: 2844: 2840: 2836: 2832: 2828: 2827: 2820: 2817: 2813: 2809: 2805: 2801: 2800: 2793: 2790: 2786: 2782: 2778: 2774: 2773: 2772:J. Org. Chem. 2765: 2762: 2758: 2754: 2750: 2746: 2745: 2738: 2735: 2731: 2727: 2726: 2719: 2716: 2712: 2708: 2704: 2703: 2696: 2693: 2687: 2682: 2678: 2674: 2670: 2663: 2660: 2656: 2652: 2648: 2644: 2643: 2636: 2633: 2629: 2625: 2621: 2617: 2616: 2609: 2606: 2602: 2598: 2594: 2590: 2589: 2588:J. Org. Chem. 2582: 2579: 2575: 2571: 2567: 2563: 2562: 2555: 2552: 2549:, p. 77. 2548: 2542: 2539: 2535: 2529: 2526: 2522: 2518: 2514: 2510: 2509: 2502: 2499: 2495: 2491: 2487: 2483: 2482: 2475: 2472: 2468: 2464: 2460: 2459: 2452: 2449: 2445: 2441: 2437: 2433: 2432: 2425: 2422: 2418: 2412: 2409: 2406:, p. 40. 2405: 2399: 2396: 2392: 2388: 2384: 2380: 2379: 2371: 2368: 2364: 2360: 2356: 2352: 2351: 2344: 2341: 2337: 2333: 2329: 2328: 2317: 2314: 2310: 2306: 2302: 2298: 2297: 2296:J. Org. Chem. 2289: 2286: 2282: 2278: 2274: 2270: 2269: 2264: 2258: 2256: 2252: 2248: 2244: 2240: 2236: 2235: 2234:J. Org. Chem. 2228: 2225: 2221: 2217: 2213: 2209: 2208: 2201: 2198: 2194: 2190: 2186: 2185: 2174: 2171: 2167: 2163: 2159: 2155: 2154: 2146: 2143: 2140:, p. 31. 2139: 2133: 2130: 2127:, p. 29. 2126: 2120: 2117: 2113: 2109: 2108: 2101: 2098: 2094: 2090: 2086: 2082: 2081: 2074: 2071: 2067: 2061: 2058: 2053: 2047: 2043: 2039: 2032: 2029: 2025: 2021: 2017: 2013: 2012: 2005: 2002: 1997: 1991: 1987: 1980: 1977: 1970: 1964: 1960: 1958: 1954: 1950: 1946: 1941: 1939: 1935: 1926: 1922: 1920: 1916: 1907: 1903: 1901: 1897: 1896:Yoshito Kishi 1893: 1889: 1884: 1882: 1878: 1869: 1865: 1863: 1859: 1858:ascorbic acid 1854: 1852: 1848: 1845: 1841: 1833: 1824: 1820: 1811: 1806: 1802: 1801: 1795: 1792: 1788: 1784: 1775: 1769: 1768:quantum yield 1761: 1756: 1752: 1748: 1745: 1744:photochemical 1741: 1737: 1734: 1733: 1729: 1724: 1720: 1718: 1709: 1705: 1703: 1699: 1695: 1691: 1682: 1677: 1673: 1670: 1667: 1663: 1662: 1658: 1653: 1646: 1642: 1639: 1635: 1631: 1627: 1626: 1625: 1623: 1622:isomerization 1619: 1618:electrophilic 1611: 1607: 1603: 1599: 1592: 1589: 1586: 1583: 1580: 1576: 1573: 1570: 1567: 1563: 1561: 1555: 1551: 1547: 1544: 1540: 1538: 1534: 1531: 1528: 1525: 1522: 1519: 1515: 1511: 1507: 1503: 1500: 1497: 1496: 1492: 1490: 1486: 1484: 1480: 1472: 1467: 1464: 1461: 1458:– Removed by 1457: 1454: 1451: 1447: 1444: 1443: 1439: 1434: 1430: 1428: 1423: 1421: 1417: 1413: 1409: 1405: 1403: 1399: 1395: 1391: 1387: 1383: 1378: 1376: 1372: 1368: 1364: 1360: 1356: 1352: 1348: 1344: 1340: 1336: 1332: 1328: 1323: 1319: 1317: 1313: 1309: 1305: 1300: 1298: 1297:1,3-propadiol 1294: 1285: 1277: 1273: 1271: 1267: 1263: 1259: 1250: 1245: 1241: 1239: 1235: 1232: 1228: 1224: 1221: 1218: 1214: 1212: 1208: 1206: 1202: 1199: 1198: 1197: 1192: 1188: 1184: 1180: 1176: 1172: 1169: 1165: 1161: 1149: 1146: 1143: 1140: 1137: 1133: 1129: 1125: 1121: 1111: 1101: 1098: 1097: 1096: 1090: 1086: 1083: 1081: 1078:. Common in 1077: 1076:glycopeptides 1073: 1069: 1067: 1062: 1058: 1054: 1050: 1047: 1039: 1037: 1033: 1030: 1026: 1024: 1020: 1017: 1013: 1009: 1005: 1001: 998: 995: 992: 991: 990: 984: 982: 980: 976: 972: 968: 964: 960: 956: 951: 949: 945: 941: 937: 933: 929: 927: 923: 919: 910: 905: 901: 896: 889: 884: 880: 878: 870: 866: 864: 860: 856: 852: 848: 844: 840: 832: 827: 824: 817: 814: 810: 806: 803: 800: 796: 793: 790: 787: 786: 785: 779: 775: 771: 768: 765: 761: 758: 754: 750: 746: 743: 740: 736: 733: 730: 727: 724: 720: 717: 715: 711: 708: 705: 702: 699: 695: 692: 691: 690: 684: 680: 677: 674: 670: 668: 664: 661: 658: 655: 651: 648: 647: 646: 640: 637: 634: 631: 627: 623: 619: 616: 613: 609: 605: 604:Triethylsilyl 602: 600: 596: 592: 588: 585:(TMS) — 584: 581: 580: 579: 573: 570: 567: 564: 561: 560:Acetoxy group 557: 554: 553: 552: 546: 541: 537: 533: 531: 527: 523: 514: 507: 506: 505: 503: 499: 495: 490: 488: 484: 483:(hemi)acetals 480: 477: 473: 469: 461: 456: 454: 448: 444: 442: 438: 433: 431: 427: 423: 419: 415: 408: 401: 397: 395: 391: 387: 382: 380: 379:benzyl groups 376: 375:hydrogenation 371: 369: 365: 364:biological pH 361: 357: 355: 351: 346: 340: 337: 334: 331: 328: 325: 322: 319: 316: 313: 310: 307: 304: 301: 298: 295: 294: 293: 287: 285: 283: 279: 267: 262: 259: 255: 248: 243: 241: 239: 234: 229: 227: 223: 219: 215: 208: 204: 200: 196: 192: 188: 184: 180: 175: 169: 162: 160: 156: 154: 150: 149:shikimic acid 146: 142: 138: 134: 130: 126: 122: 116: 114: 110: 106: 101: 97: 93: 89: 85: 81: 76: 74: 70: 66: 62: 58: 50: 46: 42: 38: 34: 30: 19: 4841: 4788: 4782: 4774:(in German). 4767: 4763: 4757: 4746: 4739: 4715: 4711: 4705: 4700: 4692: 4687: 4673:(4): 93–94. 4670: 4666: 4660: 4648: 4644: 4638: 4633: 4625: 4620: 4612: 4607: 4595: 4591: 4585: 4580: 4565: 4558: 4554: 4539: 4532: 4528: 4513: 4506: 4502: 4461: 4455: 4449: 4424: 4419: 4406: 4394: 4390: 4384: 4379: 4367: 4361: 4356: 4344: 4340: 4334: 4329: 4317: 4313: 4307: 4302: 4290: 4286: 4280: 4275: 4263: 4259: 4253: 4248: 4219: 4211: 4199: 4193: 4187: 4175: 4171: 4165: 4159: 4147: 4143: 4137: 4132: 4120: 4116: 4110: 4097: 4085: 4081: 4075: 4070: 4058: 4054: 4048: 4043: 4031: 4027: 4021: 4016: 4004: 4000: 3994: 3989: 3977: 3973: 3967: 3962: 3954: 3949: 3930: 3925: 3915: 3907: 3901: 3896: 3884: 3880: 3874: 3869: 3857: 3853: 3847: 3842: 3830: 3826: 3820: 3815: 3810:(in German). 3803: 3799: 3793: 3788: 3780: 3775: 3767: 3762: 3750: 3746: 3740: 3735: 3723: 3719: 3713: 3708: 3696: 3692: 3686: 3681: 3669: 3665: 3659: 3654: 3642: 3638: 3632: 3626: 3614: 3610: 3604: 3599: 3587: 3583: 3577: 3572: 3564: 3559: 3547: 3543: 3537: 3531: 3519: 3515: 3509: 3504: 3496: 3491: 3483: 3478: 3470: 3465: 3453: 3449: 3443: 3438: 3426: 3422: 3416: 3411: 3399: 3395: 3389: 3384: 3372: 3368: 3362: 3357: 3340: 3334: 3324: 3316: 3311: 3302: 3296: 3289:Angew. Chem. 3288: 3284: 3279: 3271: 3266: 3260: 3252: 3247: 3235: 3231: 3225: 3220: 3208: 3204: 3198: 3193: 3181: 3177: 3171: 3166: 3158: 3153: 3145: 3140: 3128: 3124: 3118: 3114: 3109: 3101: 3096: 3084: 3080: 3076: 3071: 3059: 3055: 3049: 3035: 3023: 3019: 3013: 3007: 2999: 2994: 2986: 2981: 2969: 2965: 2959: 2954: 2942: 2938: 2932: 2927: 2915: 2911: 2905: 2900: 2888: 2884: 2878: 2873: 2861: 2857: 2851: 2846: 2834: 2830: 2824: 2819: 2807: 2803: 2797: 2792: 2780: 2776: 2770: 2764: 2752: 2748: 2742: 2737: 2729: 2723: 2718: 2706: 2700: 2695: 2676: 2672: 2662: 2650: 2646: 2640: 2635: 2623: 2619: 2613: 2608: 2596: 2592: 2586: 2581: 2569: 2565: 2559: 2554: 2546: 2541: 2533: 2528: 2516: 2512: 2506: 2501: 2489: 2485: 2479: 2474: 2466: 2462: 2456: 2451: 2439: 2435: 2429: 2424: 2416: 2411: 2403: 2398: 2386: 2382: 2376: 2370: 2358: 2354: 2348: 2343: 2331: 2325: 2316: 2304: 2300: 2294: 2288: 2276: 2272: 2266: 2242: 2238: 2232: 2227: 2215: 2211: 2205: 2200: 2188: 2182: 2173: 2161: 2157: 2151: 2145: 2137: 2132: 2124: 2119: 2111: 2105: 2100: 2095:(in German). 2088: 2084: 2078: 2073: 2065: 2060: 2037: 2031: 2026:(in German). 2019: 2015: 2009: 2004: 1985: 1979: 1952: 1942: 1931: 1912: 1899: 1885: 1874: 1855: 1837: 1779: 1714: 1694:butyllithium 1686: 1675: 1629: 1615: 1562:-butylphenol 1559: 1536: 1517: 1513: 1487: 1476: 1424: 1419: 1415: 1411: 1407: 1406: 1401: 1397: 1393: 1389: 1385: 1381: 1379: 1370: 1366: 1362: 1358: 1346: 1342: 1338: 1334: 1330: 1326: 1325:Besides the 1324: 1320: 1301: 1290: 1269: 1265: 1261: 1257: 1254: 1237: 1230: 1210: 1195: 1094: 1065: 1035: 1022: 989:Carbamates: 988: 974: 970: 955:phthalimides 952: 947: 932:Amine groups 930: 915: 908: 903: 874: 836: 808: 788: 783: 738: 723:zinc bromide 688: 682: 678: 666: 644: 638: 622:acetonitrile 617: 577: 550: 534: 524:(TMS-Cl), a 519: 491: 472:nucleophiles 465: 452: 440: 434: 422:noble metals 412: 386:quinomethide 383: 372: 368:temperatures 358: 347: 344: 291: 278:carbohydrate 275: 257: 253: 230: 225: 221: 213: 212: 209:of Tyrosine. 202: 198: 190: 182: 178: 173: 157: 140: 121:biomolecules 117: 113:deprotection 112: 108: 83: 77: 60: 56: 54: 47:) during an 29: 18:Deprotection 4845:(in German) 4707:Tetrahedron 4562:Tetrahedron 4536:Tetrahedron 4510:Tetrahedron 4397:, C21–C24; 4347:, C45–C48; 4282:Tetrahedron 4228:. pp. 4077:Tetrahedron 3688:Tetrahedron 3391:Chem. Lett. 3051:Tetrahedron 2481:Tetrahedron 2263:latrunculin 1919:Danishefsky 1915:Mitomycin C 1851:oseltamivir 1585:Orthoesters 1460:Lewis acids 1355:Thioacetals 1136:methylamine 922:nucleophile 851:benzylidene 591:acetic acid 437:chromophore 336:Photolabile 187:amino group 153:oseltamivir 133:nucleotides 39:protects a 4853:Categories 4421:Org. Lett. 4255:Chem. Rev. 4167:Org. Lett. 4139:Chem. Rev. 3969:Chem. Rev. 1971:References 1862:Reichstein 1823:Phil Baran 1530:Benzhydryl 1483:oxazolines 1427:hemiaminal 1316:silica gel 1187:thiophenol 1162:in liquid 1072:morpholine 1057:piperidine 967:imidazoles 530:silica gel 426:enol ether 373:Catalytic 366:(5-9) and 139:may often 67:to obtain 3903:Synthesis 2725:Synthesis 2107:Synthesis 1909:Palytoxin 1892:palytoxin 1847:synthesis 1840:sucralose 1776:Criticism 1591:Oxazoline 1581:reagents. 1466:Dithianes 1272:-acetals. 1126:and N in 1070:, or 50% 1063:(DMF) or 1012:palladium 994:Carbamate 985:Selection 940:carbamate 936:acylation 865:acetals. 833:1,2-Diols 776:in HMPT ( 689:Acetals: 418:isomerize 392:(CAN) or 327:Oxidation 321:Reduction 84:protected 4486:17377577 4441:17555322 2265:A", in: 1938:aldehyde 1894:acid by 1636:or with 1620:attack, 1124:cytosine 1008:hydrogen 963:pyrroles 599:methanol 572:Pivaloyl 551:Esters: 498:benzoate 309:Fluoride 218:tyrosine 125:peptides 100:carbonyl 96:alcohols 4781:", in: 4494:4357378 4466:Bibcode 3336:Synlett 1934:epoxide 1881:acetone 1558:2,6-di- 1456:Acylals 1446:Acetals 1304:Acetone 1164:ammonia 1132:ammonia 1128:adenine 1110:Benzoyl 959:Indoles 900:glycine 839:glycols 566:Benzoyl 494:acetate 430:enamine 396:(DDQ). 360:Lipases 350:silicon 141:shorten 43:(as an 4492: 4484: 4457:Nature 4439: 4236: 3117:, in: 2048: 1992: 1936:to an 1672:Methyl 1612:Alkene 1539:-Butyl 1524:Benzyl 1502:esters 1499:Methyl 1450:Ketals 1375:sulfur 1351:Thiols 1341:- and 1201:Benzyl 1177:& 1160:sodium 1100:Acetyl 1089:nickel 902:. The 847:acetal 843:sugars 822:in DCM 660:Trityl 650:Benzyl 556:Acetyl 500:, and 479:ethers 468:esters 315:Enzyme 147:(e.g. 105:acetal 92:esters 45:acetal 41:ketone 4490:S2CID 4416:(PDF) 3044:-AlCl 1844:Roche 1810:Tosyl 1738:As a 1730:Other 1630:trans 1595:LiAlH 1575:Silyl 1264:– or 1246:(CAN) 1175:Nosyl 1148:Tosyl 926:bases 813:DABCO 805:Allyl 487:ether 416:will 240:). 197:and ( 179:black 123:like 49:ester 4789:1998 4764:1996 4712:1992 4645:1993 4592:1934 4566:1990 4540:1990 4514:1990 4482:PMID 4437:PMID 4391:1972 4368:1977 4341:1977 4314:1971 4287:2002 4260:1967 4234:ISBN 4230:1291 4200:2000 4172:2001 4144:1999 4117:2010 4105:TiCl 4082:1998 4055:1990 4028:1998 4001:1974 3974:1996 3908:1978 3881:1978 3854:1975 3827:1987 3800:1983 3747:1986 3720:1972 3693:1978 3666:1992 3639:1990 3611:1986 3584:1983 3544:1991 3516:1988 3450:1986 3423:1985 3396:1981 3369:1980 3341:2006 3287:In: 3232:1992 3205:1978 3178:1988 3125:1984 3081:1988 3056:1982 3020:1985 2966:1984 2939:1988 2912:1986 2885:1984 2858:1982 2831:1975 2804:1978 2777:1979 2749:1987 2730:1975 2707:1981 2647:1983 2620:1982 2593:1983 2566:1980 2513:1982 2486:1991 2463:1948 2436:1986 2383:1991 2355:1987 2332:1981 2301:1990 2273:1990 2239:1991 2212:1990 2189:1986 2158:1990 2112:1980 2085:1996 2046:ISBN 2016:1996 1990:ISBN 1953:tert 1634:zinc 1560:tert 1537:tert 1448:and 1142:Troc 1091:(0). 1053:Fmoc 1036:tert 1010:and 965:und 948:tert 909:blue 904:tert 898:BOC 857:and 809:tert 749:soft 639:tert 618:tert 547:List 303:Base 297:Acid 256:and 226:tert 222:tert 203:tert 181:). 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