Conformation of non-aromatic ring compounds—XXIV : On the geometry of the perhydrophenanthrene skeleton in some steroids

Abstract

A quantitative description of the conformation of the A,B,C,-moiety of eight steroids in terms of valency and torsional angles is given. The geometrical details of the molecules from X-ray structure determinations are compared with those obtained from theoretical considerations on appropriately substituted cyclohexane and cyclohexene rings. It is shown that the use of such building material leads to a qualitative agreement. A number of interactions present in a steroid, but not in a cyclohexane unit, prevents a quantitative agreement. The steroid skeleton (all trans) has a somewhat bent overall shape. The occurrence of conformational transmission effects is discussed and a number of rules concerning the torsional angles around junctions given.