Syntheses of 24,25-dihydroxyvitamin D2, 24,25-dihydroxy-22-dehydrovitamin D3, 25-hydroxy-24-oxo-22-dehydrovitamin D3 and 22,24,25-trihydroxyvitamin D3.

Four vitamin D2 and D3 metabolites, 24, 25-dihydroxyvitamin D2 (8), 24, 25-dihydroxy-22-dehydrovitamin D3 (10). 25-hydroxy-24-oxo-22-dehydrovitamin D3 (12) and 22, 24, 25-trihydroxy-vitamin D3 (14), were synthesized from ergosterol (1) via the hydroxyketone (4) as a common key intermediate.