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

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%).

1. custom(exotherm reaction!)
2. customThe reaction mixture was evaporated
3. customthe black residue was triturated for 30 min with Na2CO3 (saturated aqueous solution, 300 mL)
4. extractionThe reaction mixture was extracted with dichloromethane (4×250 mL)
5. dry with materialthe combined organic layer was dried over MgSO4
6. concentrationconcentrated in vacuo
7. customto give 6.64 g of crude product
8. filtrationfiltered
9. washwashed with diethyl ether
10. customThe obtained precipitate was dried in vacuo

ORD record

ord-32a4698eef0b4de799dd7001456f741f

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08772510B2