Synthesis of the non-K-region arene oxides and tetrahydro epoxides of dibenz[a,h]anthracene

Abstract

Dibenz[a,h]anthracene 1,2- and 3,4-oxides, (1a) and (2a), as well as the corresponding 1,2,3,4tetrahydro epoxides, (1b) and (2b), were synthesized from 3,4-dihydro- and 1,2-dihydrodibenz[a,h]anthracene, (12) and (17), utilizing bromohydrin ester intermediates. Compounds (12) and (17) were prepared from 3,4-dihydrodibenz[a,h]anthracen-1(2H)-one (10) and 1,2-dihydrodibenz[a,h]anthracen-4(3H)-one (15) in almost quantitative yield. An improved synthesis of (10) is described. 1H N.m.r. analysis revealed that (1a) and (2a) exist at room temperature predominantly as arene oxides and not as oxepines. Spontaneous aromatization of (1a) in aqueous solution at pH 7.4 gave a mixture of the 1- and 2-phenols, while (2a) yielded a mixture of the 3- and 4-phenols.