4-chloro-2,5-difluoroaniline

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 4-Chloro-2,5-difluoroaniline (XXXIX) (2.1 g, 12.8 mmol) was mixed with pyridine (20 ml) at 0° C., to it was dropwise added ethyl chloroformate (1.5 g, 13.8 mmol). After stirring for 2.5 hr while temperature slowly raised to room temperature, pyridine was evaporated and the residue crystallized in ice-water (100 ml). The crystals were filtered, washed with water and dried in fume hood overnight (2.7 g). 1H NMR (CDCl3, 300 MHz) 1.33 (3H, t, J=7.1 Hz), 4.23 (2H, q, J=7.1 Hz), 6.89 (1H, br), 7.12 (1H, dd, J=6.5, 6.5 Hz), 8.05 (1H, dd, J=7.8, 9.6 Hz) ppm. pyridine was evaporated the residue crystallized in ice-water (100 ml) The crystals were filtered washed with water dried in fume hood overnight (2.7 g)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 4-Chloro-2,5-difluoroaniline (XXXIX) (2.1 g, 12.8 mmol) was mixed with pyridine (20 ml) at 0° C., to it was dropwise added ethyl chloroformate (1.5 g, 13.8 mmol). After stirring for 2.5 hr while temperature slowly raised to room temperature, pyridine was evaporated and the residue crystallized in ice-water (100 ml). The crystals were filtered, washed with water and dried in fume hood overnight (2.7 g). 1H NMR (CDCl3, 300 MHz) 1.33 (3H, t, J=7.1 Hz), 4.23 (2H, q, J=7.1 Hz), 6.89 (1H, br), 7.12 (1H, dd, J=6.5, 6.5 Hz), 8.05 (1H, dd, J=7.8, 9.6 Hz) ppm. pyridine was evaporated the residue crystallized in ice-water (100 ml) The crystals were filtered washed with water dried in fume hood overnight (2.7 g)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1-Chloro-2,5-difluoro-4-nitrobenzene (XXXVIII) (17.5 g) was dissolved in acetic acid (150 ml) in a 1L 3-neck round bottom flask equipped with cooling condenser. To it iron powder (35.0 g) was added slowly while the solution was stirred by an overhead stirrer. The reaction was exothermic which occurred in less than 30 min and generated much heat that was absorbed by a cooling bath. After that, ethyl acetate (300 ml) was added and the mixture filtered. The solution was washed with water and dried over sodium sulfate. The product was purified by column chromatography (silica gel, hexane:ethyl acetate, 4:1) (14.3 g). 1H NMR (CDCl3, 300 MHz) 3.89 (2H, br), 6.56 (1H, m), 7.02 (1H, m) ppm. equipped with cooling condenser occurred in less than 30 min generated much heat that was absorbed by a cooling bath After that, ethyl acetate (300 ml) was added the mixture filtered The solution was washed with water dried over sodium sulfate The product was purified by column chromatography (silica gel, hexane:ethyl acetate, 4:1) (14.3 g)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1-Chloro-2,5-difluoro-4-nitrobenzene (XXXVIII) (17.5 g) was dissolved in acetic acid (150 ml) in a 1L 3-neck round bottom flask equipped with cooling condenser. To it iron powder (35.0 g) was added slowly while the solution was stirred by an overhead stirrer. The reaction was exothermic which occurred in less than 30 min and generated much heat that was absorbed by a cooling bath. After that, ethyl acetate (300 ml) was added and the mixture filtered. The solution was washed with water and dried over sodium sulfate. The product was purified by column chromatography (silica gel, hexane:ethyl acetate, 4:1) (14.3 g). 1H NMR (CDCl3, 300 MHz) 3.89 (2H, br), 6.56 (1H, m), 7.02 (1H, m) ppm. equipped with cooling condenser occurred in less than 30 min generated much heat that was absorbed by a cooling bath After that, ethyl acetate (300 ml) was added the mixture filtered The solution was washed with water dried over sodium sulfate The product was purified by column chromatography (silica gel, hexane:ethyl acetate, 4:1) (14.3 g)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Tin (II) chloride dihydrate (15.5 g, 68.7 mmol) was dissolved in ethyl acetate (50 mL) and 1-chloro-2,5-difluoro-4-nitrobenzene (2.65 g, 13.7 mmol) was added dropwise. The reaction mixture was then stirred at 70° C. for 1 h. The reaction mixture was then carefully added to saturated aqueous sodium bicarbonate and extracted with ethyl acetate. The organic phase was washed several more times with water, dried, filtered, concentrated and purified by flash chromatography on silica gel (hexane/diethyl ether) to give the title compound as a white solid (1.65 g, 73.9% yield): 1H NMR (CDCl3) δ 7.02 (dd, 1H), 6.57 (dd, 1H), 3.81 (br s, 2H). extracted with ethyl acetate The organic phase was washed several more times with water dried filtered concentrated purified by flash chromatography on silica gel (hexane/diethyl ether)

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Tin (II) chloride dihydrate (15.5 g, 68.7 mmol) was dissolved in ethyl acetate (50 mL) and 1-chloro-2,5-difluoro-4-nitrobenzene (2.65 g, 13.7 mmol) was added dropwise. The reaction mixture was then stirred at 70° C. for 1 h. The reaction mixture was then carefully added to saturated aqueous sodium bicarbonate and extracted with ethyl acetate. The organic phase was washed several more times with water, dried, filtered, concentrated and purified by flash chromatography on silica gel (hexane/diethyl ether) to give the title compound as a white solid (1.65 g, 73.9% yield): 1H NMR (CDCl3) δ 7.02 (dd, 1H), 6.57 (dd, 1H), 3.81 (br s, 2H). extracted with ethyl acetate The organic phase was washed several more times with water dried filtered concentrated purified by flash chromatography on silica gel (hexane/diethyl ether)