Stereoselective approach to potential scaffold of A-nor B-aromatic OSW-1 analogues via [4+2] cycloaddition of o-quinodimethane

A-nor B-aromatic steroidal skeleton was efficiently constructed by means of o -quinodimethane chemistry with exclusive stereoselectivity. The benzocyclobutene substrate for generation of the o -quinodimethane intermediate and subsequent [4+2] cycloaddition could be synthesized via ( E )-selective Julia–Kocienski olefination and diastereoselective Grignard addition reactions. The synthesized tricyclic steroid-like compound with a trans -diol substructure would be utilized for divergent syntheses of potentially antitumor OSW-1 analogues with the truncated steroidal aglycone.