Bronsted Acid-Thiourea Co-Catalysis

摘要

The thiourea-1 Brnsted acid co-catalyzed Pictet-Spengler reaction of varioustryptamines and aldehydes is reported. The au-thors assume the transformation to proceed viaBrnsted acid supported Brnsted acid catalysis (I).After formation of an iminium ion intermediate, theenantioselective, chiral counteranion-assistedcyclization occurs. Subsequent rearomatizationliberates the product and the catalysts.