Synthesis of 7H-8, 9-Dihydro-4,8-Dimethyl-Pyrano[2,3-e]Indol-2-Ones

Abstract

The synthesis of pyrrolocoumarins viz., 7H-8,9-dihydro-4,8-dimethyl-pyrano[2,3-e]indol-2-ones, a new tricyclic system (5), have been achieved from 7-amino-4-methylcoumarin (1) by tosylation, allylation and neat pyrolysis. A plausible mechanism involving amino-Claisen rearrangement followed by [3:3] sigmatropic shift has been presented.