Atroposelective synthesis of N–N axially chiral pyrrolylamides by combined-acid catalytic Paal–Knorr reaction

A general and efficient method for the construction of enantiomerically pure N-N axially chiral pyrrolylamides by utilizing the catalytic asymmetric Paal-Knorr reaction has been developed. The key to success is the use of the binary-acid catalytic system involving the dramatic synergistic effect of a Lewis acid and a chiral phosphoric acid for achieving effective stereocontrol.