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 d 4 22 23 dihydroergocalciferol ix with a yield of 1 2 g 60 and with the following characteristics 1 h nmr 400 mhz cdcl 3 u03b4ppm 0 55 3h s 18 h 3 0 78 6h dd 26 h 3 and 27 h 3 0 87 3h d 21 h 3 0 93 3h d 28 h 3 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 to a stirred solution of vitamin d 4 ix 3 0 g 7 5 mmol in 10 ml of dry pyridine was added freshly recrystallized p toluenesulfonyl chloride 3 6 g 19 mmol at 0 u00b0 c the reaction mixture was stirred at 5 u00b0 c for 24 hours and was then quenched by pouring the mixture over ice and saturated.