Syntheses of 11β- fluorocholestan-3-one derivatives

1156-1164The stereoselective syntheses of 11β-fluorocholestan-3-one 4 are described starting from enone 1. During this process, hitherto unreported fluoro derivatives 5, 6 of cholestan-3-one have been synthesized. The enones 1, 2 and 3 on treatment with 'FBr' generated in situ from polypyridiniumhydrogenfluoride (PPHF) and N-bromosuccinimide (NBS) followed by tri-n-butyltinhydride give 11β-fluorocholestan-3-one derivatives 5, 6 and 4, respectively. The survival of C-F bond during hydrogenation of 6 in the presence of Wilkinson's catalyst is a significant advantage of this methodology