Crystal and molecular structure of the bromoindole derivative of 3β-methoxy-21-keto-Δ13-serratene

Abstract

Crystals of the bromoindole derivative of 3β-methoxy-21-keto-Δ¹³-serratene, C₃₇H₅₂NOBr,C₂H₅OH, are orthorhombic, a= 10·203 ± 4, b= 11·124 ± 2, c= 31·230 ± 12 Å, Z= 4, space group P2₁2₁2₁. The structure was determined with Cu-K_α diffractometer data by Patterson, electron-density, and block-diagonal least-squares methods, the final R being 0·086 for 1459 observed reflexions. The absolute configuration was determined by the anomalous dispersion method.

The seven-membered ring adopts the chair conformation, but there is some out-of-plane distortion at the Δ¹³-double bond. The plane through the steroid nucleus is slightly bowed to minimize trans-annular methyl–methyl interactions.