ON THE SYNTHESIS OF THE 7R-OXIRANES OF 5E - AND 5Z-10-OXO-19-NORCHOLECALCIFEROL

The two title compounds 12b and 13b have been prepared by direct oxida tion of the corresponding 10-oxo-19-norcolcalciferol derivatives 3c an d 4c with MCPBA. The generation of 12b and 13b by treatment of the Del ta(7) epoxidized ethylisoxazolin adducts of 5Z- and 5E-cholecalciferol 8a, 86 and 9a, 9b with Mo(CO)(6) failed, since besides the retroaldol cleavage of the heterocycle a deoxygenation of the oxirane with reten tion of configuration to the Delta(7) double bond occurs.