Atroposelective Synthesis of Axially Chiral Thiourea and Imides by NHC-Catalyzed Desymmetrizative Amidation

Chiral thiourea, with a double hydrogen-bonding motif, emerged as attractive structural templates for asymmetric catalysis. Despite the significance, synthesis of enantioenriched thiourea predominantly relies on the nucleophilic addition of a chiral amine to isothiocyanate; catalytic synthesis of NH-free thiourea is highly desirable, albeit a formidable challenge. We herein describe NHCs-catalyzed desymmetrizative amidation of axially biaryl dialdehydes, providing structurally diversified axially chiral thiourea and imides. Sequential kinetic resolution improves the enantioenrichment of the desymmetrization product, dramatically expanding the range of applicable substrates. This strategy features a broad subtract scope and extremely excellent enantioselectivity. NHCs-catalyzed desymmetrizative amidation of axially prochiral biaryl dialdehydes provides modular platforms for synthesizing challenging axially chiral thiourea, imines, and derivatives.