'-METHYLANDROSTA-4,16-DIENO[L6,17-D]PYRAZOLE-3-ONE

In an attempt to find the structural features promoting the thermal is omerization of the N-acylated steroid[16,17-d]pyrazoles into [17,16-c] pyrazole derivatives, the X-ray structure analysis of the title compou nd, C23H30N2O3, (I), has been carried out. The steroid moiety of (I) h as the usual conformation. The dihedral angle between the planar pyraz ole ring and the N-acetyl group is very small [5.6 (2)degrees], but th e amide C-N bond seems to be substantially elongated [1.404 (3) Angstr om]. The d-pyrazole ring junction via a double bond leads to deformati ons of some bond and torsion angles, which would be decreased in the c ase of a ring junction via a single bond in the [17,16-c]pyrazole isom er.