Junjappa‐Ila annulation : α‐Oxoketene dithioacetal mediated synthesis of substituted benzotriazoles

2‐(1‐Benzyl‐1 H –1,2,3‐triazole‐4‐yl)‐3‐methylsulfanyl‐5‐oxo‐5‐substituted‐ pent ‐2‐enenitrile 3a , 3b , 3c , 3d , 3e were obtained in good yields by condensation of (1‐benzyl‐1 H ‐1,2,3‐triazole‐4‐yl)acetonitrile 1 with various α‐oxoketene dithioacetals 2a , 2b , 2c , 2d , 2e in the presence of sodium hydride. The intermediates 3a , 3b , 3c , 3d , 3e underwent facile acid‐induced cyclization in the presence of PTSA to afford the corresponding benzotriazoles 4a , 4b , 4c , 4d , 4e in moderate yields. J. Heterocyclic Chem., (2009).