Sodium hydride → HCID 22222501, compound

Participants

Reaction Steps

3,4-Difluoroaniline (5.16 g) and 5.76 g of ethyl-2-methyl acetoacetate were refluxed in toluene (80 ml) in the presence of 0.3 ml of boron trifluoride etherate for 3 hr. The reaction mixture was washed with a saturated sodium hydrogencarbonate solution and saturated brine and was dried over anhydrous sodium sulfate, and the solvent was then removed by evaporation. The resultant intermediate was refluxed in diphenyl ether for 30 min. The reaction solution was allowed to stand for cooling, and the precipitate was then collected by filtration under the reduced pressure to give 4.0 g of a mixture of 2,3-dimethyl-4-hydroxy-6,7-difluoroquinoline with 2,3-dimethyl-4-hydroxy-5,6-difluoroquinoline. In 10 ml of tetrahydrofuran was suspended 230 mg of 60% sodium hydride. The mixture of 2,3-dimethyl-4-hydroxy-6,7-difluoroquinoline with 2,3-dimethyl-4-hydroxy-5,6-difluoroquinoline (starting material 1) (1 g) was suspended in 20 ml of tetrahydrofuran, and this suspension of starting material 1 was added dropwise to the above suspension under ice cooling. The reaction mixture was stirred for one hr. Cyclopropanecarbonyl chloride (starting material 2) (600 mg) was then added thereto, and the mixture was stirred at room temperature for 15 hr. The reaction solution was poured into water, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with a saturated aqueous sodium hydrogencarbonate solution and saturated brine and was then dried over anhydrous sodium sulfate. The solvent was then removed by evaporation under the reduced pressure. The crude product thus obtained was purified on Wako Gel C-200 (200 ml; elution solvent=n-hexane-ethyl acetate (10:1)) to give 890 mg of 2,3-dimethyl-4-cyclopropanecarbonyloxy-6,7-difluoroquinoline (compound 15) and 90.6 mg of 2,3-dimethyl-4-cyclopropanecarbonyloxy-5,6-difluoroquinoline (compound 16). 1H-NMR data are shown in Table 3.

Provenance & Evidence