Studies on Organic Fluorine Compounds. LII. Synthesis and Biological Activity of 26, 26, 26, 27, 27-Pentafluoro-lα-hydroxy-27-methoxyvitamin D₃

Abstract

Replacement of one fluorine atom of the hexafluorocholesterol derivative (4) with a methoxyl group took place during the saponification of the acetyl groups of 4 with methanolic potassium hydroxide to give the pentafluoromethoxy compound (5), which was converted to the corresponding 1α-hydroxyvitamin D₃ form (6). The pentafluoromethoxy compound (6) was found to be about three times more potent than 1 a-hydroxyvitamin D₃ in displacing radio-labeled 1, 25-dihydroxyvitamin D₃ from the chick intestinal receptor, whereas the activity of 6 in response to bone calciummobilization in vitamin D-deficient rats was slightly lower than that of 1 a-hydroxyvitamin D₃.