Chiral phosphoric acid-catalyzed addition of thiols to N-acyl imines: access to chiral N,S-acetals.

The first catalytic asymmetric method to prepare enantioenriched N,S-acetals using chiral BINOL phosphoric acids is reported. The reaction combines N-acyl imines with thiols to generate products in excellent yield and enantioselectivity. The addition reaction could also be achieved with an exceptional substrate to catalyst (S/C) molar ratio. Electron-rich and electron-deficient aromatic N-acyl imines, as well as a broad range of aliphatic and aromatic thiols, showed excellent reactivity.