Functionalization of the 6,14-bridge of the orvinols - 1. Preparation and Diels-Alder reaction of 7-phenylsilylthebaines

摘要

The anion 5 of thebaine (1) reacts with small electrophiles exclusively at the 5-position (Scheme 1). Reaction of thebaine anion with a range of alkylarylsilyl chlorides showed that reaction at the 7-position was favored with increasing steric bulk, with triphenylsilyl chloride yielding only the 7-substituted product 7e (Scheme 1). Reaction of 7-(triphenyisilyl)thebaine (7e) with benzoquinone gave rise to the expected Diels-Alder adduct 8 (Scheme 2), an analog of thevinone (2) with a silyl substituent at the 6,14-etheno bridge. The presence of this substituent gives a handle for potentially functionalizing the bridge of this important class of compounds.