Nitration and bromination reactions of galbulin

Abstract

Nitration of the 1-phenyltetralin lignan, galbulin, occurs initially with dealkylative nitration at C 9 and cleavage of the C 1-C 9 bond. Subsequent reaction of the carbonium ion formed at C 1 with nitrate ion, and the degree of nitration of the aromatic rings, determine the final products. In contrast, bromination is not dealkylative and occurs initially at C 6? in ring c and subsequently at C 5 (ring A). Bromination in acetic acid in the presence of pyridine is accompanied by an unusual aromatic reaction, acetoxylation at C 8.