Enantioselective aza Michael-type addition to alkenyl benzimidazoles catalyzed by a chiral phosphoric acid

Highly enantioselective Michael-type addition (MTA) reactions between N-protected alkenyl benzimidazoles and either pyrazoles or indazoles as nitrogen nucleophiles are accomplished for the first time using chiral phosphoric acid catalyst. Theoretical studies elucidated the reaction pathway and the origin of the stereochemical outcomes, where the catalyst substituent and the N-protecting group of benzimidazole contributed to the resulting high enantioselectivity. Heterocycle squared: Highly enantioselective Michael-type addition reactions to alkenyl benzimidazoles with pyrazoles and indazoles as nitrogen nucleophiles are accomplished using a chiral phosphoric acid catalyst. Theoretical studies elucidated the reaction pathway and the origin of the stereochemical outcome. The catalyst substituent and the N-protecting group (PG) of the benzimidazole contribute to the resulting high enantioselectivity.