Novel series of 17β-pyrazolylandrosta-5,16-diene derivatives and their inhibitory effect on 17α-hydroxylase/C17,20-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/C17,20-lyase (P45017α) in vitro and neither of the regioisomers exerted efficient inhibition.

► Novel steroidal pyrazole regioisomers were synthesized.
► These compounds contain a double bond in position 16.
► The regioisomers were tested for their inhibitory activity against P45017αin vitro.