Synthesis of the Central Portion of Cycloviracin

摘要

Cycloviracin B_1 (1) was recently isolated from a soil microorganism and discovered to have activity against Herpes simplex virus. The interesting structure of the cycloviracins reveals the presence of a "core" portion composed of two glucose molecules as part of the mac-rolactone. Attached to the glycosidic core are two alkyl side chains with several 2-methylglucopyranosides. The stereogenic centers of the alkyl group at the site of attachment to the macrolactone portion and those along the alkyl side chains are currently unknown. To help elucidate the various stereogenic centers and because of the unique structure and antiviral activity, we set out to synthesize the core region of cycloviracin. In this paper, we wish to communicate our results in preparing a suitably protected glycoside intermediate 16 that served as a precursor for the stepwise construction of the cycloviracin core. This effort should aid in the determination of the two unknown stereogenic centers of the core.