反应详情

In the first step, 2,1,3-benzoxadiazole-4-carboxaldehyde is reacted with methyl acetoacetate in the presence of acetic acid and piperidine in diisopropyl ether. The reaction is carried out in diisopropyl ether under reflux with simultaneous removal of water formed during the reaction. Removal of the water from the reaction mixture enables the reaction to proceed at a faster rate. The reaction is completed at the end of theoretical amount of water removal from the reaction mixture. The completion of the reaction is determined by qualitative HPLC analysis. In this reaction methyl acetoacetate 0.9 to 1.1 mol is used for every 1.0 mol of 2,1,3-benzoxadiazole-4-carboxaldehyde, preferably 0.95 to 1.0 mol methyl acetoacetate is used for every 1.0 mol of 2,1,3-benzoxadiazole-4-carboxaldehyde. Acetic acid and piperidine are used in catalytic amount, preferably acetic acid 0.25 to 0.30 mol and piperidine 0.08 to 0.06 mol is used for every 1.0 mol of 2,1,3-benzoxadiazole-4-carboxaldehyde. This reaction goes to completion after 8 to 12 hr at reflux. The reaction mixture is then washed with dilute hydrochloric acid, followed by dilute sodium bicarbonate solution and followed by water. The crude product 2-acetyl-3-benzofurazan-4-yl-acrylic acid methyl ester is then obtained by distillation of diisopropyl ether under vacuum.

1. customformed during the reaction
2. customRemoval of the water from the reaction mixture
3. customthe reaction
4. customThe reaction is completed at the end of theoretical amount of water removal from the reaction mixture
5. temperatureat reflux
6. washThe reaction mixture is then washed with dilute hydrochloric acid