(22S)-hydroxyvitamin D4

Using ergosterol acetate as starting material, 22-hydroxylated analogues of 22,23-dihydroergosterol have been prepared via(i) selective epoxidation of the 22,23-double bond and (ii) Grignard reaction on the hexanor-22-aldehyde. (22S)-Hydroxyvitamin D4, produced upon irradiation of (22S)-22,23-dihydro-22-hydroxyergosterol, showed no significant antirachitic activity in rats.