Abstract
This review comprises of three parts : metabolism of vitamin D_3, syntheses of vitamin D metabolites, and syntheses of vitamin D analogs. In the first part, the in vitro as well as in vivo metabolism of 24,25(OH)_2D_3, the biosynthetic pathway of 25-OH-D_3 26,23-lactone, and the metabolism of vitamin D at the conjugated triene part are briefly discussed. In the second part, facile stereoselective method for introducing various structure of the side chains of vitamin D metabolites and syntheses of those side chain modified metabolites are described. Also a facile method for labeling deuterium or tritium at the 6- and 19-positions of vitamin D via its SO_2 adduct is described. In the third part, syntheses and biological implications of various vitamin D analogs are briefly discussed that include 1α-OH-D_3, 24,24-difluorovitamin D_3 analogs, and conformationally restricted analogs designed to study vitamin D conformation responsible for binding to VDR(vitamin D receptor).
