Synthesis and Biological Activity of a 1α, 25-Dihydroxyvitamin D2 Analog Bearing an Amide Group in the Side-Chain

Synthesis of a 1α, 25-dihydroxyvitamin D2 analog (3), in which the double bond in the side-chain in replaced by an amide group, is described. Condensation of a carboxylic acid (8) with an amine (6) gave an amide (9), which in turn led to 3 via several steps. The analog (3) could not bind to the chick cytosol vitamin D receptor, which indicated the importance of the hydrophobic interaction of the C(22)-C(23) double bond in 1α, 25-dihydroxyvitamin D2 (2) with the vitamin D receptor.