The structure of leudrin, and the nucleophilic substitution of its primary hydroxy group by bromine

Abstract

Leudrin (1a), present in some genera of the Proteaceae, is a pyrocatechol analogue of the phenolic spirobislactone leucodrin (1b). It has been characterized as its highly crystalline ar-dimethyl ether (1c). Leudrin can be re-formed from this derivative by demethylation with boron tribromide; under the conditions of the demethylation, it also undergoes unusual nucleophilic substitution to afford 11-bromo-11-deoxyleudrin (5a). The latter derivative affords leudrin after reaction with silver nitrate.