反应详情

To a solution of 20 (0.5 g, 2.34 mmol) in 12 ml of anhydrous DMF was added dropwise with stirring 0.243 ml (2.57 mmol) of acetic anhydride. The reaction was kept at room temperature for 3 days and then concentrated. The oily residue was dried by co-evaporation with xylene and then in vacuo to afford 0.65 g (108%) of 21 (contaminated with some DMF) as a white solid, which was sufficiently pure to be used in the next step without additional purification. 1H NMR (DMSO-d6): δ 10.81 (s, 1H), 8.00 (d, J=7.2 Hz, 1H), 7.13 (d, J=7.2 Hz, 1H), 4.62 (d, J=5.1 Hz, 1H), 4.53 (t, J=4.8 Hz, 1H), 4.02 (m, 1H), 3.73 (m, 2H), 3.53 (m, 2H), 2.09 (s, 3H), 1.80 (m, 1H), 1.10 (d, J=6.3 Hz, 3H).

1. concentrationconcentrated
2. dry with materialThe oily residue was dried by co-evaporation with xylene