Steroids and related studies. LIV. The structure of 17a-methyl-3β-pyrrolidinyl-17a-aza-D-homo-5α-androstane (HS691)

Abstract

The crystal structure of 17a-methyl-3fl-pyrrolidinyl17a-aza-D-homo-5a-androstane (HS691), C24Ha2N2, comprising two independent molecules in space group P1, has been determined using direct methods, successive electron density syntheses and least-squares analysis. The structure was refined by block-diagonal least squares to R o = 0.054, R w = 0.062 tbr 2271 observed reflections and R o = 0.075, R w = 0.089 for a total of 3290 reflections measured on a four-circle diffractometer in the 09/20 scanning mode. The two independent molecules in P1, a = 7.228 (1), b = 10.276 (2), c = 15.095 (3),/L c~ = 98.377 (8), fl = 84.690 (9), y = 99.409 (12) °, are related by a pseudo twofold axis. The two molecules have very similar geometry, the major differences being in the puckering of the pyrrolidine rings and their orientations with respect to the modified steroid skeleton. The methyl carbon atom C(20) on N(17a) is equatorial in both molecules.

Molecular Structure of a D-homoandrostanyl Steroid Derivative: Single Crystal and Powder Diffraction Analyses

“…The Cambridge Structural Database (CSD) was consulted with the purpose of obtaining the geometries of analogous molecular fragments. 18,19 The A, B, and C ring system (Figure 1) was found in epiandrosterone (5R androstan-3β-ol-17-one, refcode ANDRON 20 and the fragment corresponding to the D cycle was found in the MPYRAN10 entry (17a-methyl-3β-pyrrolidinyl-17a-aza-D-homo-5R-androstane 21 ). These fragments were assembled and completed with the side groups attached to the D ring using the Materials Studio Vizualizer program [version 3.2.0.0, ref 22] in order to obtain the molecular geometry for STNH.…”