Oxalyl chloride → Ethyl 5-(4-tert-butylbenzyl)-1,2,4-oxadiazole-3-carboxylate

Participants

Reaction Steps

A mixture of 2-(3-tert-butylphenyl)acetic acid (0.728 g; 3.78 mmol) and oxalyl chloride (0.352 mL; 4.16 mmol) in dichloromethane (8 mL) with few drops of DMF was stirred at room temperature for 3 hours and added to a mixture of ethyl 2-amino-2-(hydroxyimino)acetate (0.500 g; 3.78 mmol) and N,N diisopropylethylamine (1.05 mL; 6.06 mmol) in dichloromethane (10 mL) at −15° C. The reaction mixture was stirred at room temperature for 60 h and poured into a mixture of ice and water. The organic layer was separated, dried over MgSO4 and concentrated under reduced pressure. The residue was refluxed in a sealed tube with pyridine (18 mL) for 20 h and concentrated under reduced pressure. The crude material was purified by flash chromatography on silica (eluent 20 to 100% ethyl acetate in heptane) to yield 0.422 g (30%) of the title compound as a yellow solid.

Provenance & Evidence