Studies on amine oxide rearrangements: regioselective synthesis of pyrano[3,2-e]indol-7-one

Abstract

A number of hitherto unreported pyrrolocoumarin derivatives 7a–h, a new tricyclic system, have been synthesised from 6-aminocoumarin 1 by successive tosylation, methylation, detosylation, prop-2-ynylation and treatment with m-chloroperoxybenzoic acid. Compounds 7a–h have been converted into methoxy derivatives 8a–h by simple treatment with methanol.