Oxalyl chloride → Ethyl 3-methylpyrazine-2-carboxylate

To a solution of 3-methyl-pyrazine-2-carboxylic acid (10 g) (commercially available) and N,N-dimethylformamide (“DMF”) (1 drop) in dichloromethane (20 ml) at ambient temperature was added drop wise oxalyl chloride (2.57 ml). The reaction mixture was stirred at ambient temperature for 1 hour. The reaction mixture was concentrated and the residue dissolved in dichloromethane (20 ml). Triethylamine (4.04 ml) was added to this solution followed by drop wise addition of ethanol (10 ml). The reaction mixture was stirred at ambient temperature for one hour and then concentrated. The residue was purified by chromatography on silica gel (eluent: 0-10% v/v ethyl acetate in iso-hexane) to give 3-methyl-pyrazine-2-carboxylic acid ethyl ester (9.85 g). MH+=167, RT=0.73 min (Method A). 1H-NMR (400 MHz, CDCl3): 8.61 (d, 1H), 8.54 (d, 1H), 4.49 (q, 2H), 2.85 (s, 3H), 1.46 (t, 3H) ppm.

1. concentrationThe reaction mixture was concentrated
2. dissolutionthe residue dissolved in dichloromethane (20 ml)
3. additionTriethylamine (4.04 ml) was added to this solution
4. additionfollowed by drop wise addition of ethanol (10 ml)
5. stirringThe reaction mixture was stirred at ambient temperature for one hour
6. concentrationconcentrated
7. customThe residue was purified by chromatography on silica gel (eluent: 0-10% v/v ethyl acetate in iso-hexane)

ORD record

ord-a437006e63384b9bbcaa70d99ca90a8c

Source dataset

uspto-grants-2013_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08569301B2