Synthesis of a bridged benzodiaza[l4]annulene by reaction of 4,6-bisbromomethyl-5,2,8-ethanylylidene-5H-1,9-benzodiaracycloundecine with dimethyl acetonedicarboxylate

Abstract

Reaction of 4,6-bisbromomethyl-5,2,8-ethanylylidene-5H-1,9-benzodiazacycloundecine (1) under basic conditions with dimethyl acetone-1,3-dicarboxylate gives the ester (10) by 1,3-dialkylation. Oxidation of the ester (10) affords the bridged annulenone (19). The reaction of the dibromide (1) with the dimethyl ester of 2,2′-sulphinylbisacetic acid (12) or of 2,2′-sulphonylbis acetic acid (11) gives products not by 1,3-dialkylation but by gem-dialkylation.