Structure and conformation of 5-deoxy-5-hydroperoxy-5-epitelekin and 5-epitelekin

Abstract

The crystal and molecular structures of 5-deoxy-5-hydroperoxy-5-epitelekin (1) and 5-epitelekin (2) were determined by direct methods from 1 160 and 1 188 independent reflections, respectively, and refined to R 0.043 and 0.066. Both crystals are orthorhombic, space group P 2₁2₁2₁. In both compounds the cis-decalin system shows a chair–chair conformation, of steroid-like type in (1) and of non-steroid type in (2), with the substituents at C(5) and C(10) in a β-orientation. A justification of the conformational preferences shown by the two derivatives is proposed. The γ-lactone ring, cis-fused at C(8), is puckered in both molecules, being of the A-type in (1) and of the S-type in (2).