Palladium(<scp>ii</scp>)-catalysed total synthesis of naturally occurring pyrano[3,2-<i>a</i>]carbazole and pyrano[2,3-<i>b</i>]carbazole alkaloids

Abstract

Seven naturally occurring pyranocarbazole alkaloids (pyrayafoline A-E, O-methylmurrayamine A and O-methylmahanine) have been obtained by total synthesis using a palladium(II)-catalysed oxidative cyclisation of a diarylamine to an orthogonally diprotected 2,7-dihydroxycarbazole as key step.