Asymmetric Organocatalytic Protonation of Silyl Enolates Catalyzed by Simple and Original Betaines Derived from Cinchona Alkaloids. Issue 34 (24th October 2013)

• Record Type: Journal Article
• Authors: Claraz, Aurélie; Landelle, Grégory; Oudeyer, Sylvain; Levacher, Vincent
• Is Part Of: European journal of organic chemistry. Issue 34(2013)
• Page Start: 7693
• Page End: 7696
• Publication Date: 2013-10-24
• Subjects: Organocatalysis -- Betaines -- Protonation -- Asymmetric catalysis -- Ion pairs; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201301345
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: The asymmetric protonation of silyl enolates derived from tetralone, benzosuberone, and cyclohexanone has been successfully achieved by using simple and original betaine catalysts derived from Cinchona alkaloids (quinine and quinidine series) to afford the desired α‐substituted ketones in high yields and moderate enantioselectivities. The ease of implementation of this approach along with the easy accessibility of the betaine catalyst (four steps from cheap and commercially available quinine or quinidine) make this approach very appealing for the preparation of enantioenriched α‐monosubstituted carbonyl compounds. Abstract : The organocatalytic enantioselective protonation of silyl enolates has been achieved by using simple and original betaines derived from Cinchona alkaloids as catalysts and phenol as the achiral proton source to yield enantioenriched α‐monosubstituted ketones with up to 62 % ee .