Access to arylurazoles bearing both central and C–N axial chirality via asymmetric desymmetrization catalyzed by chiral phosphoric acid

We report an asymmetric desymmetrization of 4-aryl-1,2,4-triazole-3,5-diones (ATADs) through conjugate addition of pyrazolones catalyzed by chiral phosphoric acid. This reaction simultaneously constructs central and C-N axial chirality, affording atropisomeric arylurazoles with good yields and high stereoselectivities (up to 87% yield, 18 : 1 dr, 99% ee). The method exhibits broad substrate scope (28 examples), offering an efficient and novel strategy for accessing diverse atropisomeric N-heteroarenes.