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Asymmetric 1,4-Addition of Oxazolones to Nitroalkenes by Bifunctional Cinchona Alkaloid Thiourea Organocatalysts: Synthesis of α,α-Disubstituted α-Amino Acids

✍ Scribed by José Alemán; Andrea Milelli; Silvia Cabrera; Efraim Reyes; Karl Anker Jørgensen

Publisher
John Wiley and Sons
Year
2008
Tongue
English
Weight
322 KB
Volume
14
Category
Article
ISSN
0947-6539

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✦ Synopsis

Abstract

An easy and simple synthetic approach to optically active α,α‐quaternary α‐amino acids using asymmetric organocatalysis is presented. The addition of oxazolones to nitroalkenes catalyzed by thiourea cinchona derivatives provides the corresponding α,α‐quaternary α‐amino acid derivatives with good yields, excellent diastereoselectivities (up to 98 % dr), and from moderate to good enantioselectivities (up to 92 % ee). The reaction can be performed on a large scale. The optically active oxazolone–nitroalkene addition products can be opened in a one‐pot reaction to the corresponding ester–amide derivatives. Additional transformations are also presented, such as the synthesis of amino esters, amino acids, and transformation into 3,4‐disubstituted pyrrolidin‐2‐ones.

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Enantioselective Synthesis of α-Amino Ac
Enantioselective Synthesis of α-Amino Acids and Monosubstituted 1,2-Diamines by Conjugate Addition of 4-Phenyl-2-oxazolidinone to Nitroalkenes
✍ Denis Lucet; Stéphane Sabelle; Olivier Kostelitz; Thierry Le Gall; Charles Miosk 📂 Article 📅 1999 🏛 John Wiley and Sons 🌐 English ⚖ 376 KB 👁 1 views

The addition of the potassium salt of (R)-or (S)-4-phenyl-products were converted into α-amino acids and monosubstituted 1,2-diamines of high enantiomeric purity. 2-oxazolidinone to monosubstituted nitroalkenes proceeded with very good diastereoselectivity. Several of the addition derivatives are in