- Selective α-amination and α-acylation of esters and amides via dual reactivity of O-acylhydroxylamines toward zinc enolates
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Selective α-amination and α-acylation of esters and amides have been developed, employing O-acylhydroxylamines as a dually reactive aminating and acylating reagent. Treatment of zinc enolates with O-acylhydroxylamines provides solely 1,3-dicarbonyl compounds under mild conditions. Introduction of a copper catalyst into the system shifts the reactivity entirely, yielding α-amination products exclusively.
- McDonald, Stacey L.,Wang, Qiu
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supporting information
p. 2535 - 2538
(2014/03/21)
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- New C-glycosylated α-amino acid synthesis by addition reaction of an amino acid organozinc reagent on carbohydrate-derived aldehydes
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Two unreported C-glycosylated amino acid structures could be prepared by addition of an amino acid organozinc on carbohydrates bearing an aldehyde function. For this purpose, a new iodinated amino acid bearing a four-carbon side chain was conveniently prepared in two steps. Conversion into the corresponding organozinc reagent was optimal in acetonitrile using zinc/copper activated with 1,2-dibromoethane and trimethylsilyl chloride. A protocol was developed for the addition of this organozinc compound to simple aldehydes in acetonitrile using BF3 · OEt2 as a Lewis acid. When applied to riboside and glucoside aldehyde derivatives, this protocol led to new C-glycosylated amino acids in acceptable yields. Copyright Taylor & Francis Group, LLC.
- Boutard, Nicolas,Labeguere, Frederic,Vidal, Yves,Lavergne, Jean-Pierre,Martinez, Jean
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experimental part
p. 1461 - 1471
(2012/05/05)
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- Chemoenzymatic synthesis of enantiomerically pure (2S,3R,4S)-4- hydroxyisoleucine, an insulinotropic amino acid isolated from fenugreek seeds
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A short six-step synthesis of (2S,3R,4S)-4-hydroxyisoleucine (1a) with total control of stereochemistry is reported, the last step being the enzymatic resolution by hydrolysis of a N-phenylacetyl lactone derivative using the commercially available penicillin acylase G immobilized on Eupergit C (E-PAC). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Rolland-Fulcrand, Valerie,Rolland, Marc,Roumestant, Marie-Louise,Martinez, Jean
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p. 873 - 877
(2007/10/03)
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- Use of bis-(chiral α-methylbenzyl)glycine esters for synthesis of enantiopure β-hydroxyamino esters
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(Matrix presented) Aldol reactions using bis-(chiral α -methylbenzyl)glycine esters with aldehydes gave excellent diastereoselectivity. Thus, an enantiopure ribosylglycine was prepared for the synthesis of analogues of the natural antibiotics muraymycin.
- Yamashita, Ayako,Norton, Emily B.,Williamson, R. Thomas,Ho, Douglas M.,Sinishtaj, Sandra,Mansour, Tarek S.
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p. 3305 - 3308
(2007/10/03)
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- STEREOSELECTIVE SYNTHESIS OF t-BUTYL 2-AMINO-2,5-DIDEOXY-L-LYXO-PENTANOATE: FORMAL SYNTHESIS OF L-DAUNOSAMINE
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Enantiomerically pure t-Butyl 2-amino-2,5-dideoxy-L-lyxo-pentanoate 4c is synthesized via the highly diastereoselective MgBr2 mediated addition of dibenzylamino acetate silylketene acetal 2 to O-benzyl lactic aldehyde 3.The synthesis of γ-lactone 5c, a known intermediate in the synthesis of L-daunosamine, is also described.
- Banfi, Luca,Cardani, Silvia,Potenza, Donatella,Scolastico, Carlo
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p. 2317 - 2322
(2007/10/02)
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