O-nitroso aldol synthesis:: Catalytic enantioselective route to α-aminooxy carbonyl compounds via enamine intermediate

The approach using pyrrolidine enamine as substrate has been studied for this synthesis, and an important catalyst structural feature has been developed. After survey of pyrrolidine-based Bronsted acid catalyst, tetrazole catalyst (3f) was found to be optimal in synthesis of aminooxy carbonyl compounds in high yields, with complete enantioselectivity not only for aldehydes but also for ketones.