Efficient Proline-Catalyzed Michael Additions of Unmodified Ketones to Nitro Olefins

Here we describe the proline-catalyzed Michael addition of unmodified ketones to nitro olefins. This novel reaction provides γ-nitro ketones in modest enantioselectivity yet excellent yields

Proline-Catalyzed Asymmetric Aldol Reactions between Ketones and α-Unsubstituted Aldehydes

With this communication we extend the methodology of proline-catalyzed direct asymmetric aldol reactions to include α-unsubstituted aldehydes as acceptors. This important aldehyde class gives the corresponding aldols in 22−77% yield and up to 95% ee when the reactions are performed in pure acetone or in ketone/chloroform mixtures. On the basis of these results we have developed a concise new synthesis of (S)-ipsenol

Highly enantioselective synthesis of 1,2-amino alcohol derivatives via proline-catalyzed Mannich reaction

Here we report a new catalytic asymmetric synthesis of oxazolidin-2-ones 4 and Cbz-protected 1,2-amino alcohols 5. Our sequence is based on the chemistry of previously unknown 5-acyloxy-oxazolidin-2-ones, which are obtained via proline-catalyzed direct asymmetric three-component Mannich reaction and Baeyer-Villiger oxidatio

The proline-catalyzed direct asymmetric three-component Mannich reaction: Scope, optimization, and application to the highly enantioselective synthesis of 1,2-amino alcohols

We have developed proline-catalyzed direct asymmetric three-component Mannich reactions of ketones, aldehydes, and amines. Several of the studied reactions provide β-amino carbonyl compounds (Mannich products) in excellent enantio-, diastereo-, regio-, and chemoselectivities. The scope of each of the three components and the influence of the catalyst structure on the reaction are described. Reaction conditions have been optimized, and the mechanism and source of asymmetric induction are discussed. We further present application of our reaction to the highly enantioselective synthesis of 1,2-amino alcohols