Chemistry of the Coccoidea. VIII. Synthesis of the ancient dyestuff kermesic acid and of related anthraquinones

Abstract

The insect anthraquinones kermesic acid (3) and laccaic acid D (2) have been synthesized efficiently, as have the plant anthraquinones aloesaponarin-I (4) and -11 (33). The syntheses were based on regiospecific Diels-Alder addition of the silyloxy dienes (10) and (11) to simpler quinones. Regiospecificity was controlled by 2(3)-chloro groups in the dienophiles or, for addition to certain naphthoquinones, by a hydroxy group peri to carbonyl.