PURPOSE: To produce the titled compound useful as a synthetic intermediate for antihypercalcemic agent, osteogenesis promoting agent and tumor cell proliferation suppressing agent, by reducing an epoxy-hydroxycholest-en-oic acid ester.
CONSTITUTION: The objective compound of formula II [R21 and R31 are R2 and R3; R41 is H or OR51 (R51 is R21 or R31)] can be produced by reducing 25,26-epoxy-23-hydroxycholest-5-en-27-oic acid ester preferably with lithium aluminum hydride and, if necessary, subjecting the reduction product to deprotection and/or protection reaction. The ester is a compound of formula I [R1 is H, (substituted) 1W10C alkyl or (substituted) 3W10C cycloalkyl; R2 and R3 are H, tri(1W7C hydrocarbon)silyl or a group forming acetal bond or ester bond with 0 atom of OH group; R4 is H or OR5 (R5 is R2 or R3)], its steric isomer relating to 23 and 25 positions or their mixture.
TANAKA TOSHIO
KUROZUMI SEIJI
