2-Bromo-beclometasone dipropionate

In the crystal structure of 2-bromo-beclometasone dipropionate [systematic name: (8S,9R,10S,11S,13S,14S,16S,17R)-2-bromo-9α-chloro-11-hydr-oxy-10,13,16-trimethyl-3-oxo-17-[2-(propion-yloxy)acet-yl]-6,7,8,9,10,11,12,13,14,15,16,17-dodeca-hydro-3H-cyclo-penta-[a]phenanthren-17-yl propionate], C(28)H(36)BrClO(7), the six-membered ring with the 1,4-diene-3-one composition is planar (r.m.s. deviations = 0.03 and 0.04 Å for the two independent mol-ecules), whereas the remaining six-membered rings have chair conformations. Each of the independent mol-ecules self-associates via O-H⋯O(propionate) hydrogen bonding, generating a supra-molecular chain running along the b axis. The crystal is twinned, with the monoclinic unit cell emulating an orthorhomic crystal system; the major twin component constitutes approximately 60%.