α-Oxoketene dithioacetals mediated heteroaromatic annulation protocol for benzoheterocycles: an efficient regiocontrolled synthesis of highly substituted and annulated indazoles

An efficient regiocontrolled synthesis of highly substituted and annulated indazoles involving base induced addition–elimination of 1,3-diphenyl-5-cyanomethylpyrazole to a variety of acyclic and cyclic α-oxoketene, followed by acid assisted cycloaromatization of the resulting conjugate adducts has been reported.