Nomenclature of synthetic steroids

At the present time, a convenient and generally accepted nomenclature has been developed for steroid compounds [125-127] according to which they are named as derivatives of a number of fundamental structures (generally hydrocarbons) and the configuration of the substituents with respect to the angular methyl groups is denoted by the indices a (trans) and /3 (cis). 

These symbols also correspond to the absolute configuration of the substituents. However, this nomenclature in its original form is not capable of describing the synthetic steroid compounds with which we must deal in performing a total synthesis. In actual fact, the existing rules of nomenclature are suitable for denoting only one optically active form, and for antipodes or racemates it is necessary to have recourse to excessively complex names. This can be explained by the following examples. 

Natural progesterone, A -pregnene-3,20-dione, has the structure expressed by formula (296). Its antipode (297, 298) must be named by the existing rules of nomenclature as 8a, 9)8,10j3,13a, 14jS,17Q -A -pregnene-3,20-dione. This name is not only difficult to understand but it is completely unsuitable for use since no name is left for the racemic compound it can be described only by a combination of the names of the two enantiomers. Consequently, it is natural that with the development of work on the total synthesis of steroids much attention has been devoted to the question of nomenclature. 

Some of the proposals put forward have not obtained general acceptance. Thus, Nazarovas proposed modified nomenclature [128] according to which each of the four possible 5, 14 -isomers of the basic hydrocarbons in the series of normal and D-homosteroids was given its own name has not been accepted. In addition to an considerable over-all complication of nomenclature, this proposal did not take into account the possibility of isomerism at Cg, Cg, Cjoj 3.nd Cjg. 

The q( system is clearer and more readily understood for steroids. The desirability of the retention of this system for naming products of total 

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