5-bromo-4-chloro-2-methyl-1-oxidopyridin-1-ium

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to room temperature, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to room temperature, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to rt, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: To a solution of 5-bromo-2-methyl-4-nitropyridine N-oxide (558 mg, 2.41 mmol) in DCM (3 mL) at 0° C. was added dropwise a solution of POCl3 (1.3 mL, 7.22 mmol) in DCM (3.2 mL). After 12 h at 25° C. the solution was added to ice, adjusted to pH ˜8 and extracted several times with DCM. The combined organic fractions were dried over Na2SO4, concentrated and purified via column chromatography (silica, 1.5% MeOH in DCM) yielding the title compound (426 mg, 80%) as a white solid: LCMS (ES) m/z=224 (M+H)+. After 12 h at 25° C. the solution was added to ice extracted several times with DCM The combined organic fractions were dried over Na2SO4 concentrated purified via column chromatography (silica, 1.5% MeOH in DCM)

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to rt, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to room temperature, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: 3.0 mL trifluoroacetic anhydride were added dropwise at 10° C. to 2.6 g (12 mmol) 5-bromo-4-chloro-2-methylpyridine-1-oxide in 30 mL DCM. The reaction mixture was stirred for 5 days at RT. After the addition of MeOH the reaction mixture was evaporated down, the residue was combined with 15% potassium carbonate solution and extracted several times with EtOAC. The combined organic phases were dried on sodium sulphate and evaporated down. was evaporated down extracted several times with EtOAC The combined organic phases were dried on sodium sulphate evaporated down

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

Procedure: 4.2 mL (46 mmol) phosphorus oxychloride in 20 mL DCM were added dropwise at 10° C. to 3.6 g (15 mmol) 5-bromo-2-methyl-4-nitropyridine-1-oxide in 30 mL DCM. The reaction mixture was then refluxed for 5 h, then added to ice water and adjusted to a pH of 10 with 4N aqueous sodium hydroxide solution. The organic phase was separated off and the aqueous phase was extracted twice more with DCM. The combined organic phases were dried on sodium sulphate and evaporated down. The residue was stirred into petroleum ether, the precipitate formed was suction filtered and dried. The reaction mixture was then refluxed for 5 h The organic phase was separated off the aqueous phase was extracted twice more with DCM The combined organic phases were dried on sodium sulphate evaporated down the precipitate formed filtered dried

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

Procedure: A solution of 4-chloro-5-bromo-2-picoline-N-oxide (23.9 g) in dichloromethane (250 ml) was cooled to 10° and trifluoroacetic anhydride (25 ml) added over 20 minutes. The mixture was allowed to warm to ambient temperature, and stand for 7 days. After cooling to 10°, methanol (100 ml) was added, and the solution stripped. The residue was treated with water (150 ml), basified with saturated aqueous sodium carbonate to pH 10, and extracted with ethyl acetate (2×150 ml). The combined extracts were dried (MgSO4). stripped, and triturated with ether to give 4-chloro-5-bromo-2-hydroxymethylpyridine, 16.58 g. m.p. 109°-10°. After cooling to 10° extracted with ethyl acetate (2×150 ml) The combined extracts were dried (MgSO4) triturated with ether

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

Procedure: A solution of 5-bromo-4-nitro-2-picoline-N-oxide (30.0 g) in dichloromethane (250 ml) was cooled at 10°, and a solution of phosphoryl chloride (35.5 ml) in dichloromethane (200 ml) added over 15 minutes. The mixture was heated under reflux for 5 hours, allowed to cool to ambient temperature, and allowed to stand for 16 hours. After pouring onto ice (300 ml) and stirring for 15 minutes, the mixture was basified to pH 10 using concentrated aqueous sodium hydroxide. The organic phase was separated off, and the aqueous phase further extracted with chloroform (2×100 ml). The combined organic phases were dried (K2CO3) and stripped to a solid, which was triturated with petroleum ether (40-60), filtered, washed and dried to yield 4-chloro-5-bromo-2-picoline-N-oxide, 24.08 g, m.p. 121°-4° C. The mixture was heated under reflux for 5 hours After pouring onto ice (300 ml) The organic phase was separated off the aqueous phase further extracted with chloroform (2×100 ml) The combined organic phases were dried (K2CO3) was triturated with petroleum ether (40-60) filtered washed dried

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to room temperature, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated

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

Procedure: 5-Bromo-2-methyl-4-nitropyridine oxide (7.0 g, 30 mmol) was refluxed in conc. HCl (80 mL) for 16 hrs. The mixture was allowed to cool to room temperature, partially concentrated and then neutralized by NaOH (10N) to pH 7. The crude was partitioned between CHCl3 and water. The organic solution was separated, dried and concentrated to yield 5-bromo-4-chloro-2-methylpyridine oxide as a white solid (6.71 g). MS [M+H]+: 223.7; tR=1.91 min. (method 1). partially concentrated The crude was partitioned between CHCl3 and water The organic solution was separated dried concentrated