反应详情

A flame-dried, 250 mL round bottom flask was charged, under argon, with 2 (10 g, 39.6 mmol) and this was dissolved in 50 mL of anhydrous pyridine and the flask was protected from light. To this solution was added acetic anhydride (9.3 mL, 98.8 mmol) dropwise at a rate of 0.5 mL/minute. The solution was stirred at room temperature for 30 minutes at which time all of the starting material had been consumed. The solvent was evaporated with reduced pressure and then toluene was added to remove excess pyridine. Evaporation of the solvent in vacuo gave 11.5 g (99%) of 3 as an off-white solid. Rf=0.74 (33% ethyl acetate/hexane). Mp 74.0-75.0° C. 1H NMR (400 MHz, DMSO-d6): δ9.83 (s, 1), 7.53 (dd, J=1.6 Hz, 8.4 Hz, 1), 7.39 (d, J=2.0 Hz, 1),), 7.17 (d, J=8.4 Hz, 1), 4.07 (t, J=6.4 Hz, 2), 4.00 (pt, J=6.4 Hz, 6.8 Hz, 2), 3.83 (s, 3), 2.00 (s, 3) 1.74 (m, 2), 1.58 (m, 2), 1.4-1.35 (m, 4) ppm.

1. customhad been consumed
2. customThe solvent was evaporated with reduced pressure
3. additiontoluene was added
4. customto remove excess pyridine
5. customEvaporation of the solvent in vacuo