Preparation method of benzo [e] [1, 3] oxazine-2, 4-diketone
A benzo and oxazine technology, which is applied in the field of preparation of benzo[e][1,3]oxazine-2,4-dione, can solve the problems of high environmental harm and high industrialization cost, and achieve non-toxic effect , Simple operation, low price effect
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[0037] A first object of the present invention is to provide a preparation method of benzide [e] [1, 3] uase-2,4-diketone, including the following steps, basic conditions, 2-hydroxybenzamide and (Boc) 2 O Under the action of the catalyst, the reaction was reacted in an organic solvent to obtain the benzene [E] [1,3] uxine-2,4-diketone. Carbonylation cycloal reagent diaphrate di-tert-butyl-butyl (BOC) 2 O As a preferred protective reagent, it is used to introduce tert-butoxycarbonyl (BOC) protective agent in synthesis. Under anhydrous conditions, it can be reacted with a thickness of 2-hydroxybenzamide with a weak nucleophilicity.
[0038] In one embodiment of the invention, the chemical reaction flow is:
[0039]
[0040] In one embodiment of the invention, under basic conditions, starting materials and (BOC) at 2-hydroxybenzamide 2 O At the action of the catalyst, the reaction was reacted in an organic solvent to obtain an intermediate tert-butyl ester; an intermediate tert-but...
Embodiment 1
[0057] One kind benzo [e] [1,3] oxazine-2,4-dione Preparation of the following steps:
[0058]
[0059] 500mL four reaction flask was added 2-hydroxybenzamide (13.7g, 0.1mol, 1.0equiv), N, N- dimethylformamide (DMF) (58.5mL), pyridine (5mL at 20-25 ℃, 0.062mol, 0.6equiv), was stirred at this temperature-time (Boc) 2 O (24.0g, 0.11mol, 1.1equiv), was stirred at this temperature for 2h, TLC showed the starting material disappeared, the reaction was stopped, water was added (292 mL), and extracted with ethyl acetate (100mL * 3), the combined extracts washed with water (50 mL ), dried at 40 ℃ the ethyl acetate solution was concentrated to give a residue. The residue, toluene (100 mL), warmed to 90 ℃, stirred for 4h, cool down to 20-25 ℃, suction filtration to give a white crystalline solid (12.5 g), yield 76.7%.
Embodiment 2
[0061] One kind benzo [e] [1,3] oxazine-2,4-dione Preparation of the following steps:
[0062] 2L four reaction flask was added 2-hydroxybenzamide (137g, 1mol, 1.0equiv), N, N- dimethylformamide (DMF) (1370mL), pyridine (50mL, 0.62mol at 20-25 ℃, 0.6equiv), was stirred at this temperature-time (Boc) 2 O (240g, 1.1mol, 1.1equiv), was stirred at this temperature for 2h, then warmed to 80 ℃, stirred for 4h, cool down to 20-25 & deg.] C, was added water (1370mL), the pH adjusted to 1-2 with hydrochloric acid, there white solid precipitated, IH stirred at this temperature, to give a white solid by suction filtration, washed with 1% hydrochloric acid, and dried in a forced air 60 deg.] C 8h, to give a white powder (131 g), yield 80%, HPLC chromatogram as figure 1 , The result indicates that the method of the present invention obtained by preparing benzo [e] [1,3] oxazine-2,4-dione purity is over 99%.
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