Synthesis of 22,23-epoxyvitamin D2(22,23-epoxyergocalciferol)
Abstract
Heating Diels–Alder adducts of steroidal-5,7-dienes and 4-phenyl-1,2,4-triazoline-3,5-dione with mineral base in an appropriate solvent at 120 °C gives the corresponding steroidal-5,7-dienes in high yields. This method is applied to a synthesis of 22,23-epoxyergosterols. The irradiation of this compound followed by thermal isomerization gives 22,23-epoxyvitamin D2.