Crystal and molecular structure of 5α-acetoxy-6β-bromohexahydrophysalin A

Abstract

5α-Acetoxy-6β-bromohexahydrophysalin A is shown to have a novel 13,14-seco-16,24-cyclo-C₂₈-steroidal structure by X-ray crystal structure analysis. The crystals are monoclinic, space group P2₁, with two molecules of C₃₀H₃₇O₁₂Br,2CH₄O in the unit cell of dimensions a= 24·09 ± 0·05, b= 7·60 ± 0·02 c= 8·74 ± 0·03 Å, β= 96·0°± 0·2°. The crystal structure was elucidated by the heavy-atom method and the atomic co-ordinates were refined by Fourier and least-squares calculations. The final R value over 3716 independent reflexions is 0·105. The absolute configuration was determined by the anomalous dispersion method.