Confirmation of the Involvement of C_<20>-Carbonium Cation during the Hot Acid Hydrolysis of Pregnanediol Disulfate (Clinical Analysis on Steroids. XXIII

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The formation of a C_<20>-carbonium cation during the hot acid hydrolysis of pregnanediol disulfate (1b) and the role of this cation in the rearrangement reactions were examined. Hydrolysis of 1b in boiling 3_N hydrochloric acid in oxygen-18 water gave 17α-ethyl-17β-methyl-18-nor-5β-androst-13-en-3α-ol (2) as the main product, together with pregnanediol (1a), 17α-methyl-D-homo-5β-androstane-3α, 17aβ-diol (3), 17α-methyl-17aβ-chloro-D-homo-5β-androstan-3α-ol (4), 5β-pregn-20-en-3α-ol (5a), 5β-pregnane-3α, 20β-diol (10), and other minor degradation products. The isotope content of these products was determined by gas chromatography-mass spectrometry. Among then, 3 and 10 were quantitatively labeled with ^<18>O at 17aβ- and 20β-ol, respectively, and 1a was 74% labeled at 20α-ol. No uptake of ^<18>O into 3α-ol of the products was observed. These results confirm the formation of the C_<20>-carbonium cation from 1b. Hydrolysis of 5β-pregn-20-en-3α-ol sulfate (5b), which is considered to be the conjugated base of the C_<20>-cation, gave 2 as the main product accompanied with 1a, 3,4,5a, and 10. This result suggests that the C_<20>-carbonium cation plays an important role as an intermediate to D-homosteroids as well as to the Δ^<15>-olefin 2.
1982-12-25