Ethanol → Vitamin D4

22,23-dihydroergosterol (VIII) (2.0 g, 5.0 mmol) was dissolved in a solution of diethyl ether and benzene (4:1, 600 ml) and irradiated (Hannovia immersion lamp, 450 watts) with stirring under argon in a water-cooled quartz vessel for three hours. The solution was concentrated in vacuo to yield a gummy solid, which was redissolved in 100 ml. of ethanol and heated at reflux under argon for eight hours. Then, the solution was concentrated in vacuo and the residue was adsorbed on a silica gel column and eluted with 30% ethyl acetate in hexane to afford vitamin D4 (22,23-dihydroergocalciferol) (IX) with a yield of 1.2 g. (60%) and with the following characteristics: 1H NMR: (400 MHz, CDCl3), δppm 0.55 (3H, s, 18--H3) 0.78 (6H, dd, 26--H3 and 27--H3) 0.87 (3H, d, 21--H3) 0.93 (3H, d, 28--H3) 3.94 (1H, m, 3--H) 4.82 (1H, m (sharp), 19--H), 5.04 (1H, m (sharp), 19--H), 6.04 (1H, d, 7--H) 6.24 (1H, d, 6--H).