Novel series of 17β-pyrazolylandrosta-5,16-diene derivatives and their inhibitory effect on 17α-hydroxylase/C(17,20)-lyase.

The Claisen condensation of 3β-acetoxypregna-5,16-dien-20-one (1) with ethyl formate in the presence of sodium methylate in pyridine is known to lead to 3β-hydroxy-21-hydroxymethylidenepregna-5,16-dien-20-one (2) in good yield. With the methods described for the preparation of the saturated D-ring pyrazolyl series, the reactions of 2 with phenylhydrazine and its p-substituted derivatives in acetic acid resulted in mixtures of two steroidal regioisomers, the 1'-aryl-3'-pyrazolyl-(4a-e) and 1'-aryl-5'-pyrazolyl (5a-e) steroids. Compounds 4a-e are unknown in the literature. The arylpyrazoles produced were tested against 17α-hydroxylase/C(17,20)-lyase (P450(17α)) in vitro and neither of the regioisomers exerted efficient inhibition.