Direct asymmetric aldol reactions in brine with recyclable fluorous β-aminosulfonamide organocatalysts
摘要:
Fluorous organocatalyst 3 promotes direct asymmetric aldol reactions of ketones with aldehydes in brine, leading to the synthesis of the corresponding anti-aldol products in high yields with up to 96% ee. Fluorous organocatalyst 3 is easily recovered by solid-phase extraction using fluorous silica gel and can be reused up to five times without purification. (C) 2011 Elsevier Ltd. All rights reserved.
The asymmetricconjugateaddition of nitroalkanes to α,β-unsaturated ketones in the presence of a catalytic amount of a novel sulfonamide–thiourea organocatalyst resulted in the corresponding γ-nitro carbonyl products in high yields with excellent enantioselectivities (up to 97% ee).
Asymmetric direct vinylogous aldolreactions of furan-2(5H)-one with aldehydes in the presence of a catalytic amount of novel squaramide–sulfonamide organocatalyst resulted in the corresponding addition products with high to excellent enantioselectivities. This is the first successful report illustrating an example of highly stereoselective reactions using a squaramide–sulfonamide organocatalyst.