| abstract |
A vitamin D3 derivative represented by general formula (I), wherein Rs represent each independently hydrogen, tri(C1-C7 hydrocarbyl)silyl, C2-C8 acyl or a group forming an acetal bond with the oxygen atom of a hydroxyl group; A represents groups (a), (b) or (c) wherein R1 represents methyl or methylene, provided when R1 is methylene, the bond between it and the 3-position of the lactone ring it a double bond; R2 represents hydrogen or C¿1?-C3 alkyl; and R?3¿ represents hydrogen, or R?2 and R3¿ may be combined together to represent an optionally substituted methylene group. |