Brønsted Acid-catalyzed Addition and Cyclization Reaction with Imine

From Aqueous Reaction to Enantioselective Reactions

Abstract

Brønsted acid-catalyzed nucleophilic addition and cycloaddition reaction with imines are described. In the first part, HBF₄-catalyzed Mannich-type reaction of silyl enolate with aldimine in aqueous media is described. When SDS was used as a surfactant, an organic solvent was not necessary and the carbon-carbon bond forming reactions proceeded smoothly in water alone as a solvent. Aza Diels-Alder reaction also took place in aqueous media by Brønsted acid catalysis. In the latter part, chiral Brønsted acidcatalyzed enantioselective reactions are presented. We prepared a cyclic phosphoric acid diester starting from (R) -BINOL. It was found that the acid exhibited excellent catalytic activity as a chiral Brønsted acid in the Mannich-type reaction, hydrophosphonylation, and aza Diels-Alder reaction.