Oxidant-controlled divergent transformations of 3-aminoindazoles for the synthesis of pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals

Abstract

The oxidant-controlled divergent reactivity of 3-aminoindazoles is presented herein. Diverse functionalized pyrimido[1,2-b]-indazole derivatives were obtained with good yields via a Lewis-acid promoted [3 + 3] annulation reaction between ketene dithioacetals and 3-aminoindazoles. When the reaction was performed using the Cu/[O] catalytic system, new reactivity for the ring-opening of 3-aminoindazoles via C–N bond activation was achieved, which enables the olefinic C–H arylation of ketene dithioacetals under mild conditions.