Microwave assisted InCl3 mediated regioselective synthesis of highly functionalized indolylpyran under solvent-free condition and its chemical transformation to indolyltriazolylpyran hybrids

A series of novel, highly functionalized indolylpyrans has been synthesized via InCl3 catalyzed microwave irradiation of 3-cyanoacetylindoles, aromatic aldehydes with NMSM under solvent- free condition. Further, the synthesized azidoindolylpyrans undergo [3+2] cycloaddition reaction with different phenyl acetylenes to give indolyltriazolylpyran hybrids in excellent yields. This domino transformation, generating CC, CC, CO, CN, and NN bonds with a stereo center in minimum reaction steps. In particular the attractive feature of this approach is the synthesis of three important bioactive heterocyclic frameworks, indole–pyran–triazole hybrids, under mild reaction conditions, making this novel strategy highly useful in our diversity oriented synthesis (DOS).