A vitamin D.sub.3 derivative represented by the following formula: wherein, R is, independently, a hydrogen atom, tri(C.sub.1 to C.sub.7 hydrocarbon)silyl group, C.sub.2 to C.sub.8 acyl group, or group forming an acetal bond together with an oxygen atom of a hydroxyl group, A is ##STR1## where, R.sup.1 is a methyl group or methylene group, and when R.sup.1 is a methylene group, the bond between the R.sup.1 and the 3-position of the lactone ring is a double bond, R.sup.2 is a hydrogen atom or C.sub.1 to C.sub.3 alkyl group, R.sup.3 is a hydrogen atom, or R.sup.2 and R.sup.3 together indicate a substitutable single methylene group.
一种
维生素D.sub.3衍
生物,其
化学式如下:其中,R独立地表示氢原子、三(C.sub.1到C.sub.7的烃基)
硅基、C.sub.2到C.sub.8酰基或与羟基的氧原子一起形成
缩醛键的基团。A为##STR1##其中,R.sup.1为甲基基团或亚甲基基团,当R.sup.1为亚甲基基团时,R.sup.1与内酯环的3位之间的键为双键,R.sup.2为氢原子或C.sub.1到C.sub.3烷基,R.sup.3为氢原子,或R.sup.2和R.sup.3一起表示可替代的单亚甲基基团。