Ethoxalyl chloride → Ethyl [1,2,4]triazolo[1,5-a]pyridine-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a light red solution of 1,2-diaminopyridinium 2,4,6-trimethylbenzenesulfonate (10.9 g, 35.2 mmol) in pyridine (50 mL) was added ethyl 2-chloro-2-oxoacetate (9.62 g, 7.84 mL, 70.5 mmol) at RT (exotherm reaction!). The light red solution turned into a dark red solution. The mixture was heated to 100° C. and stirred overnight. The reaction mixture was evaporated and the black residue was triturated for 30 min with Na2CO3 (saturated aqueous solution, 300 mL). The reaction mixture was extracted with dichloromethane (4×250 mL) and the combined organic layer was dried over MgSO4 and concentrated in vacuo to give 6.64 g of crude product. The crude product was suspended in diethyl ether (30 mL), filtered and washed with diethyl ether. The obtained precipitate was dried in vacuo to give the product as light brown solid (6.1 g, 31.9 mmol, 90.6%).

Provenance & Evidence