4,5-dibromobenzene-1,2-diamine

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: 4,5-dibromobenzene-1,2-diamine (100 mg, 0.38 mmol) and tert-butyl 4-formylpiperidine-1-carboxylate (160 mg, 0.76 mmol) were stirred for 1 hour in 2,2,2trifluoroethanol. Then Solvent was evaporated and product was purified on silica gel using EA/hex (1/1). Yield: 20 mg. m/z 657.1, rt. 4.2 min. Then Solvent was evaporated product was purified on silica gel m/z 657.1, rt 4.2 min.

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

Procedure: 4,5-dibromobenzene-1,2-diamine (100 mg, 0.38 mmol) and tert-butyl 4-formylpiperidine-1-carboxylate (160 mg, 0.76 mmol) were stirred for 1 hour in 2,2,2trifluoroethanol. Then Solvent was evaporated and product was purified on silica gel using EA/hex (1/1). Yield: 20 mg. m/z 657.1, rt. 4.2 min. Then Solvent was evaporated product was purified on silica gel m/z 657.1, rt 4.2 min.

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

Procedure: Following the procedure of Example 9, 5 g. of 3,4-dibromo-6-nitroaniline were reduced in anhydrous ethanol with Raney nickel to yield 4,5-dibromo-o-phenylenediamine which was not isolated but mixed immediately with 2.47 g. of 2-ketoglutaric acid. One hundred ml. of ethanol were added and the mixture heated to refluxing temperature for 3 hours. 3 gms. of β-(6,7-dibromo-3,4-dihydro-3-oxo-2-quinoxaline)propionic acid were obtained melting at 249°-250° C. The free acid was converted to the corresponding ethyl ester by the procedure of Example 8. Ethyl β-(6,7-dibromo-3,4-dihydro-3-oxo-2-quinoxaline)propionate thus prepared melted at 189°-190° C.

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

Procedure: Five grams of 4,5-dibromo-2-nitroaniline were suspended in 200 ml. of anhydrous ethanol to which was added about 10 g. of Raney Nickel. The hydrogenation mixture was placed in a low pressure hydrogenation apparatus at a hydrogen pressure of 55 psi. A rapid uptake of hydrogen occurred which ceased after about 25 minutes, at which time the deep yellow color originally present was discharged indicating complete reduction of the nitro group to an amine group. The hydrogenation was continued for another half hour and the hydrogenation mixture was then worked up by filtering off the catalyst, washing the filtered catalyst, and stripping the volatile constituents from the filtrate. A yield of 4.1 g. of 4,5-dibromo-o-phenylenediamine was obtained. The hydrogenation was continued for another half hour by filtering off the catalyst washing the filtered catalyst

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

Procedure: Five grams of 4,5-dibromo-2-nitroaniline were suspended in 200 ml. of anhydrous ethanol to which was added about 10 g. of Raney Nickel. The hydrogenation mixture was placed in a low pressure hydrogenation apparatus at a hydrogen pressure of 55 psi. A rapid uptake of hydrogen occurred which ceased after about 25 minutes, at which time the deep yellow color originally present was discharged indicating complete reduction of the nitro group to an amine group. The hydrogenation was continued for another half hour and the hydrogenation mixture was then worked up by filtering off the catalyst, washing the filtered catalyst, and stripping the volatile constituents from the filtrate. A yield of 4.1 g. of 4,5-dibromo-o-phenylenediamine was obtained. The hydrogenation was continued for another half hour by filtering off the catalyst washing the filtered catalyst

Conditions: temp:125.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 4,5-dibromo-1,2-phenylenediamine (1.862 g, 7.0 mmol) and oxalic acid dihydrate (1.06 g, 8.4 mmol) in 2N HCl (100 mL) was heated at 125° C. for 2 h then allowed to cool to 25° C. The solid was collected by vacuum filtration, washed with water and dried at 40° C. under 1 mmHg for 10 h affording 2.053 g (92%) of the title compound as a light brown powder. 1H NMR (DMSO-d6) 11.995 (s, 2H), 7.361 (s, 2H). to cool to 25° C The solid was collected by vacuum filtration washed with water dried at 40° C. under 1 mmHg for 10 h

Conditions: temp:75.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 4,5-dibromo-2-nitroaniline (3.35 g, 11.32 mmol) in EtOAc (150 mL) was added stannous chloride dihydrate (12.8 g, 56.74 mmol), the mixture was stirred at 75° C. for 16 h, then allowed to cool to room temperature and poured into ice-water (about 150 mL). To the mixture was added 1N aq NaOH with vigorous stirring to take the pH to 9 (pH paper). The resulting thick yellow white emulsion was extracted with EtOAc (3×100 mL). The organic extracts were combined, washed with brine (2×50 mL), dried (over Na2SO4) and evaporated to dryness. The residual solid was dried under 1 mmHg at 40° C. for 14 h giving 2.92 g (97%) of 4,5-dibromo-1,2-phenylenediamine as a yellowish powder. Mp 149°-50° C. IR (KBr) 3400, 1623, 1489, 1394, 1271, 868 cm-1. 1H NMR (DMSO-d6) 6.754 (s, 2H), 4.867 (s, 4H). to cool to room temperature with vigorous stirring The resulting thick yellow white emulsion was extracted with EtOAc (3×100 mL) washed with brine (2×50 mL) dried (over Na2SO4) evaporated to dryness The residual solid was dried under 1 mmHg at 40° C. for 14 h

Conditions: temp:75.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 4,5-dibromo-2-nitroaniline (3.35 g, 11.32 mmol) in EtOAc (150 mL) was added stannous chloride dihydrate (12.8 g, 56.74 mmol), the mixture was stirred at 75° C. for 16 h, then allowed to cool to room temperature and poured into ice-water (about 150 mL). To the mixture was added 1N aq NaOH with vigorous stirring to take the pH to 9 (pH paper). The resulting thick yellow white emulsion was extracted with EtOAc (3×100 mL). The organic extracts were combined, washed with brine (2×50 mL), dried (over Na2SO4) and evaporated to dryness. The residual solid was dried under 1 mmHg at 40° C. for 14 h giving 2.92 g (97%) of 4,5-dibromo-1,2-phenylenediamine as a yellowish powder. Mp 149°-50° C. IR (KBr) 3400, 1623, 1489, 1394, 1271, 868 cm-1. 1H NMR (DMSO-d6) 6.754 (s, 2H), 4.867 (s, 4H). to cool to room temperature with vigorous stirring The resulting thick yellow white emulsion was extracted with EtOAc (3×100 mL) washed with brine (2×50 mL) dried (over Na2SO4) evaporated to dryness The residual solid was dried under 1 mmHg at 40° C. for 14 h

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

Procedure: Five grams of 3,4-dibromo-6-nitroaniline were suspended in 200 ml. of anhydrous ethanol to which was added about 10 g. of Raney nickel. The hydrogenation mixture was placed in a low pressure hydrogenation apparatus at a hydrogen pressure of 55 psi. A rapid uptake of hydrogen occurred which ceased after about 25 minutes, at which time the deep yellow color originally present had been discharged indicating complete reduction of the nitro group to an amino group. The hydrogenation was continued for another half hour and the hydrogenation mixture was then worked up by filtering off the catalyst, washing the filtered catalyst, and stripping the volatile constituents from the filtrate. A yield of 4.1 g. of 4,5-dibromo-o-phenylenediamine was obtained. The hydrogenation was continued for another half hour by filtering off the catalyst washing the filtered catalyst