Crystal structure of crispolide diacetate, a 4,14-cyclogermacranolide with a secondary peroxy ester moiety

Abstract

The crystal structure of crispolide diacetate (1b), a 4,14-cyclogermacranolide bearing a secondary peroxy ester group, was determined by direct methods from 1 612 reflections, and refined to R= 0.041. The crystals are orthorhombic, space group P2₁2₁2₁. The methyl group at C(4) and the hydroxy group at C(5) are cis-oriented on the β-face of the eight-membered ring, in accordance with the proposed biogenetic derivation for the unique terpenoid skeleton. The secondary peroxy ester group adopts a conformation different from that found in solution and in the solid state for tertiary peroxy esters.