| 摘要 |
<p>The invention aims at providing vitamin D3 derivatives which exhibit excellent physiological activities for drugs including remedies for skin diseases such as psoriasis and lowered calcium-increasing activities. Specifically, vitamin D derivatives of the general formula (1) are provided wherein X is oxygen or sulfur; R1 is hydrogen or a group of the general formula (2) R2 is hydrogen or alkyl; R3 and R4 are each hydrogen or alkyl, or alternatively R3 and R4 may together form a double bond between the 16- and 17-positions; R5 is hydrogen or -OR13 (wherein R13 is hydrogen or a protecting group); and R6 is hydrogen or a protecting group.</p> |
