A Novel Hydrogen-Bonding Catalyst Class with Helical Chirality

Significance

Takenaka and colleagues report the synthesis and application of a new hydrogen bond donor catalyst 1. The novelty of the catalyst lies in the combination of a relatively unexplored 2-amino-pyridinium moiety as an effective hydrogen bond donor with a chiral environment based on helicity. The Michael addition of 4,7-dihydroindoles 2 to nitro­olefins 3 was used to demonstrate the potential of the new catalyst, whereby high yields and generally excellent enantioselectivity were observed even at low catalyst loading (2 mol%). One product of the reaction was also elaborated to the monoamine oxidase inhibitor 5.