X-Ray analysis of pristimerol bis-p-bromobenzoate, a derivative of the triterpene quinone methide pristimerin

Abstract

Chemical studies on the structure of pristimerin, an unusual triterpenoid quinone methide, have been confirmed by an X-ray study of pristimerol bis-p-bromobenzoate, which crystallises in space group P2₁, with Z= 2 in a unit cell of dimensions a= 20·43 ± 0·02, b= 6·35 ± 0·01, c= 17·76 ± 0·02 Å, β= 118·5 ± 0·2°. The structure was solved by the heavy-atom method and refined to R 0·14, for 1686 observed reflections. The data suggest the absolute configuration to be that expected on biogenetic grounds.