反应详情

A solution of 6-chloro-3,4-dihydro-4-oxo-2H-1-benzopyran (3.285 g), N,N-dimethylformamide dimethyl acetal (8.568 g), and triethylamine (2.727 g) in benzene (36 ml) was refluxed with stirring for 1 hour and then about three-fourths of the solvent was distilled slowly at atmospheric pressure over a period of approximately 1 hour. To the residue was added benzene (36 ml) and the solvent was distilled again. The residue was dissolved in a mixture of chloroform and ethyl acetate, treated with activated charcoal, and evaporated in vacuo. The residual solid was washed with a mixture of diethyl ether and ethyl acetate to give 6-chloro-3,4-dihydro-3-dimethylaminomethylene-4-oxo-2H-1-benzopyran (2.73 g).

1. distillationabout three-fourths of the solvent was distilled slowly at atmospheric pressure over a period of approximately 1 hour
2. additionTo the residue was added benzene (36 ml)
3. distillationthe solvent was distilled again
4. dissolutionThe residue was dissolved in a mixture of chloroform and ethyl acetate
5. additiontreated with activated charcoal
6. customevaporated in vacuo
7. washThe residual solid was washed with a mixture of diethyl ether and ethyl acetate