SYNTHESES OF ACTIVE FORMS OF VITAMIN-D-4 AND VITAMIN-D-7

1alpha,25-Dihydroxyvitamin D4 (22,23-dihydro-1alpha,25-dihydroxyvitami n D2) (1) and D7 (24-epi-22,23-dihydro-1alpha,25-dihydroxyvitamin D2) (3) were synthesized via 25-hydroxyvitamin D4 (18a) and D7 (18b) respe ctively. Condensation of phenylsulfonyl derivatives (6a,b) with 22-iod o derivative (13) obtained from ergosterol followed by deprotection of hydroxyl groups and reductive desulfonylation of coupling product (14 a,b) and elimination of the protecting group of ergost-6-ene nucleus o n 15a,b afforded 5,7-diene (16a,b). Irradiation of 16a,b and thermal i somerzation of 25-hydroxyprevitamin D4 (17a) and D7 (17b) gave 18a and 18b. Conversion of 18a,b into 25-hydroxycyclovitamin D4 (19a) and D7 (19b), allylic oxidation of 19a,b, acetolysis of 1-hydroxycyclovitamin D4 (20a) and D7 (20b), and removal of protecting groups of hydroxyl g roups of acetolysis product (21a,b) produced 1 and 3. 1-alpha-Hydroxyv itamin D4 (2) and D7 (4) were prepared via vitamin D4 (18c) and D7 (18 d).