反应详情

At room temperature, acetic anhydride (108 μL) was added to a suspension of 2-methoxy-4-(4-phenyl-4,5,6,7-tetrahydro-benzothiazol-2-ylamino)-benzoic acid hydrazide (130 mg, 0.33 mmol) in dimethylformamide (5 mL). The mixture was stirred for 40 hours and evaporated to dryness. The residue was taken up in 10% w/w (3 mL) phosphorous pentoxide in methanesulfonic acid (prepared by mixing 5 g phosphorous pentoxide and 30 mL methanesulfonic acid and stirring for 2 h at 90° C.) and stirred for 18 hours. The mixture was poured into 75 ml water, neutralized to pH 5-6 with 32% aqueous sodium hydroxide and the precipitate filtered off. The solid was dissolved in ethyl acetate (30 mL), washed four times with water and once with brine, dried with magnesium sulfate and concentrated in vacuo, affording the title compound (69 mg, 65%) as an off-white solid. NMR (CDCl3, 300 MHz): δ (ppm)=7.74 (d, 1H), 7.61 (d, 1H), 7.31-7.15 (m, 5H), 6.82 (dd, 1H), 4.03 (m, 1H), 3.34 (m, 3H), 2.73 (m, 2H), 2.50 (m, 3H), 2.14 (m, 1H), 1.79 (m, 3H). MS ISP (m/e): 419.1 (100) (M+H)+.

1. customevaporated to dryness
2. customwas taken up in 10% w/w (3 mL) phosphorous pentoxide in methanesulfonic acid (prepared by mixing 5 g phosphorous pentoxide and 30 mL methanesulfonic acid and stirring for 2 h at 90° C.)
3. stirringstirred for 18 hours
4. additionThe mixture was poured into 75 ml water
5. filtrationthe precipitate filtered off
6. dissolutionThe solid was dissolved in ethyl acetate (30 mL)
7. washwashed four times with water
8. dry with materialonce with brine, dried with magnesium sulfate
9. concentrationconcentrated in vacuo