New short step synthesis of A,B-aromatic oxasteroids by intra- and intermolecular Diels–Alder reactions of 1,2-naphthoquinone dimethides generated from substituted 1,2-cyclobutanaphthalenes

Abstract

A simple, highly efficient synthesis of A/B aromatic 16-oxasteroids by either an intra- or inter-molecular Diels–Alder reaction of 1,2-naphthoquinone dimethides, generated by the thermolysis of methyl cyclobuta [a] naphthalene- 2-carboxylate or cyclobuta [a]naphthalen-2-ylmethanol, is described.