CRYSTAL AND MOLECULAR-STRUCTURE OF A PREGNADIENE DERIVATIVE

The crystal and molecular structure of a new synthetic steroid derivat ive have been studied by X-Ray diffraction methods. Ethyl 21-acetoxy 1 1 beta- hydroxy-1,4-pregnadiene-3,20-dione-(22S) - 16 alpha,17 alpha-o rthoacetate, C27H36O8, crystallized in the monoclinic system, space gr oup P2(1), a = 7.454(1), b = 14.982(3), c = 11.808(2)Angstrom, beta = 106.65(3)degrees, Z = 2. Structure was solved by direct methods and re fined to the final R = 0.054 for 2060 observed reflections. The new ch irality center at C(22) atom shows the S configuration but conformatio n of the E - ring enclosed in the C(22) atom is comparable with those found for the (22R) diastereoisomer of the other similar compound.