The Isolation of 5a-Pregnane-3& ZOP-diol 20-Sulfate and Its Hydrolysis to Uranediol (I7&!lethyl-D-

In 1938 Marker, Rohrmann, and Little (2) isolated from the urine of pregnant mares a new isomer of pregnanediol that they called uranediol. Ten years later, Klyne (3) obtained from the same source a sulfuric acid ester that yielded uranediol on acid hydrolysis. The structure of the free compound was determined by Klyne (4), who showed that it was a 17a-methyl-nhomo-5cr-androstane-3fl,17a&diol (Fig. 2, Via). The configuration at C-17a is not known with certainty but may well be p, as was proposed (5) on the basis of a comparison of optical rotations with those of n-homosteroids that lack the adjacent asymmetrical center at C-17.’ Some interest attaches to the biological origin of uranediol because it is a major, if not the predominant, neutral steroid that has been obtained from the urine of pregnant mares (5).2 In spite of its unusual n-homo structure, uranediol was considered to be a natural product and not an artifact because relatively mild procedures were used in the isolation of the conjugate. This view (4) was accepted by others (6, 8). The need to re-examine this problem arose when we observed the ready conversion of 3P-acetoxy-5a-pregnan-2Ofl-ol p-toluenesulfonate (Fig. 1, la) to uranediol3-acetate 17a-formate (Fig. 1, 11~) on heating with formic acid (9).3 As this rearrangement