Thermolysis of allene-1,1-dicarboxamides: acceleration of the intramolecular Diels–Alder reaction by intramolecular hydrogen bonding and a novel bicyclo[2.2.2]- to bicyclo[3.2.1]-alkadiene rearrangement

Abstract

Allene carboxanilides (5) with an additional geminal secondary carbamoyl group undergo intramolecular Diels–Alder reactions at rather low temperature (80 °C) to furnish the tricyclic lactams (6), which, in turn, isomerize to give the tricyclic lactams (8) at about 130 °C.