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

Abstract

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.