Asymmetric Addition of Thioglycolic Acid to Nitro Olefins Catalyzed by Cinchona Alkaloids

Article abstract of DOI:10.1021/jo00322a016

Thioglycolic acid (1) has been shown to undergo asymmetric addition to (2-nitroethenyl)benzene (2) in the presence of a cinchona alkaloid as a catalyst.By selection of reaction conditions, enantiomeric yields of up to 58percent were obtained.Evidence is presented which supports the idea that the interaction between the carboxyl group of 1 and the active site of the catalyst (quinuclidine nitrogen) exerts a favorable effect on the extent of asymmetric induction.When methyl 7-nitrohept-6-enoate (10) was used as an acceptor, (S)-13 was obtained in 37percent ee with quininecatalyst.Also studied was the asymmetric addition of 1 to 1-methoxy-2-(2-nitroethenyl)benzene (8) and (2-nitro-1-propenyl)benzene (9).