Studies on Steroids. LI. Stereoselective Introduction of 22- and 24-Hydroxyl Function in the Steroidal Side Chain

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Osmium tetroxide oxidation of the 22-olefin (4) and reaction of sodium dimethylsulfonium methylide with the 22-aldehyde (3a) afforded stereoselectively the 22S-and 22R-epoxides (7a and 7b), respectively. Those epoxide can be led to the 22R- and 22S-hydroxy steroides by Grignard reaction. Inversion of the configuration of hydroxyl group on C-22 and C-24 positions was achieved in high yield by means of superoxide displacement reaction.