6,7-DIHYDROXY-6,7-DIHYDROCANRENONE ISOMERS: IMPROVED SYNTHESIS AND PROTON NMR STUDY

Article abstract of DOI:10.1016/0039-128X(89)90078-0

The synthesis in improved yields of one 6,7-epoxide and three 6,7-dihydroxycanrenone derivatives is described.Canrenone was the starting material for all derivatives and was obtained by acid-catalyzed lactonization of potassium canrenoate.The epoxidation of canrenone to 6α,7α-epoxycanrenone by m-chloroperbenzoic acid was improved by addition of a free radical inhibitor.This epoxide was efficiently cleaved to 6β,7α-dihydroxy-6,7-dihydrocanrenone by perchloric acid in a dioxane-water mixture; 6β,7β- and 6α,7α-dihydroxy-6,7-dihydrocanrenone were obtained by OsO4 oxidation of canrenone in ether-pyridine and subsequent reduction of the osmates by hydrogen sulfide.The stereochemistry of the products obtained from the reaction of osmium tetroxide with the 6,7-double bond of steroidal 4,6-dien-3-ones has been a controversial issue for some time.A detailed proton-NMR study of the three diol derivatives unequivocally confirmed the proposed stereochemical structure.