Catalytic Atroposelective Synthesis of C–N Axially Chiral Pyrazolyl Pyrroles via <i>De Novo</i> Construction of a Pyrrole Ring

The catalytic atroposelective synthesis of five–five-membered C–N axially chiral heterobiaryls featuring the de novo construction of a pyrrole ring was reported. This chiral phosphoric-acid-catalyzed asymmetric Paal–Knorr reaction of 5-aminopyrazoles with 1,4-diketones delivered C–N axially chiral pyrazolyl pyrroles in good yields (up to 96%) with excellent enantioselectivities (up to 97% ee). This work establishes an efficient strategy for constructing five–five-membered C–N axially chiral pyrazole scaffolds and enriches the family of C–N axially chiral molecules.