Synthesis of 4-trifluoromethylsteroids: A novel class of steroid 5α-reductase inhibitors

A concise synthetic approach to 4-trifluoromethyl steroids, a novel class of steroid 5α-reductase inhibitors, is described. Direct trifluoromethylation of steroid olefinic bromide with methyl fluorosulfonyl-difluoroacetate was used as a key step in the synthesis. The compound 4 exhibited highly inhibitory activity than Finasteride in in vitro assay.