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).