Chiral arylaminophosphonium barfates as a new class of charged brønsted acid for the enantioselective activation of nonionic Lewis bases.

Heterochiral [7.7]-P-spirocyclic arylaminophosphonium barfates have been designed as a novel charged, cationic Brønsted acid catalyst, and their catalytic and stereocontrolling abilities have been clearly demonstrated in the development of the unprecedented, highly enantioselective conjugate addition of arylamines to nitroolefins. This study uncovers a new function of chiral tetraaminophosphonium cations and its potential synthetic utility, thereby providing a new avenue to the molecular design of chiral charged Brønsted acid catalysts and their applications.