9α-Bromo analog of beclometasone dipropionate monohydrate.

In the crystal structure of (8S,9R,10S,11S,13S,14S,16S,17R)-9α-bromo-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 monohydrate, C(28)H(37)BrO(7)·H(2)O, which has a 9α-Br atom in place of the 9α-Cl atom of monohydrated beclometasone dipropionate, one six-membered ring is planar (r.m.s. deviation = 0.02 Å) owing to its 1,4-diene-3-one composition, whereas the two other six-membered rings each have a chair conformation. The organic mol-ecule and water mol-ecules engage in hydrogen-bonding inter-actions, generating a helical chain running along the c axis of the ortho-rhom-bic unit cell.