Application of ultrasound in carbohydrate chemistry. Synthesis of optically pure functionalised hexahydro-anthracenes and -naphthacenes

Abstract

Reactions of the carbohydrate enone (5) with the o-xylylenes derived from 1,2-bis(bromomethyl)benzene and 2,3-bis(bromomethyl)naphthalene by treatment with zinc powder under ultrasound irradiation gave the tri- and tetra-cyclic products (6) and (7), which were converted into the hexahydro-anthracene and -naphthacene derivatives (18) and (19) which are related to several important natural products; in particular, the latter compound has the carbon framework, A-ring functionality, and stereochemistry similar to those of some anthracyclinones.