Ethyl Acetate → Methyl 2-chloro-5-nitroisonicotinate

Participants

Reaction Steps

To a solution of 2-chloro-4-methyl-5-nitropyridine (Aldrich Chemical Co.) (5.0 g, 29.0 mmol) in concentrated sulfuric acid (60 mL) with stirring at 0° C., was added a solution of sodium dichromate dihydrate (14.3 g, 1.65 eq) in concentrated sulfuric acid (100 mL) at a rate which kept the internal temperature less than 10° C. After addition was complete, the reaction mixture was stirred from 0° C. to room temperature over 6 hours. By TLC, the reaction was not complete, so additional sodium dichromate dihydrate (8.4 g, 1 eq) was added directly to the solution at 0° C. The resulting solution was stirred from 0° C. to room temperature overnight. The reaction was complete by TLC the next morning, and it was poured into a mixture of ice (1 L) and EtOAc (900 mL). The resulting mixture was stirred for about 10 minutes and then the layers were separated. The organic layer was washed with brine (2×600 mL), and the EtOAc layer was dried over magnesium sulfate and filtered. With stirring at room temperature, trimethylsilyl diazomethathane (2.0M in hexanes, 15 mL) was added to the EtOAc filtrate. The resulting mixture was stirred at room temperature for 30 min. By TLC, there was no acid remaining, and then MeOH (150 mL) was added and the solution stirred for 30 minutes. The solution was concentrated and then EtOAc (700 mL) was added to the residue which was dried over magnesium sulfate, filtered, concentrated and pumped to give the title compound (1A) as an off-white powder (5.79 g, M+=216, M.P.=60.5–64.1° C.).

Provenance & Evidence