Conformational studies. Part 6. X-Ray crystal structure of 3,3-dimethoxy-19-norandrosta-5(10),6-dien-17-one: an exception to the diene helicity rule

Abstract

The crystal structure of the title compound (1d) has been unequivocally defined by X-ray crystallography. Crystals are orthorhombic, space group P2₁2₁2₁, with Z= 4 in a unit cell of dimensions a= 6.042(1), b= 13.469(3), c= 21.634(5)Å. The structure was solved by direct methods and refined to a final R of 0.036 for 845 unique observed reflections.

The cisoid diene system in this compound is right-handed, but the c.d. curve is negative: the diene, and two cognate derivatives, thus constitute exceptions to the diene helicity rule.