Triethylamine → Dimethyl 3-phenyl-4,5-isoxazoledicarboxylate

Participants

Reaction Steps

To a solution of (Z)-N-hydroxybenzimidoyl chloride (467 mg, 3 mmol) and dimethyl but-2-ynedioate (0.374 mL, 3.00 mmol) in Et2O (10 mL) at rt was added dropwise over 5 minutes Et3N (0.460 mL, 3.30 mmol). The reaction mixture became a thick suspension and was stirred at rt for 2 hr. After filtration, the filtrate was concentrated to an oil that was chromatographed on a 24 gm Isco silica gel cartridge, eluting with a 0-25% EtOAc/Hex gradient. The pure fractions were concentrated to afford dimethyl 3-phenylisoxazole-4,5-dicarboxylate (780 mg, 2.99 mmol, 100% yield) as a colorless oil. HPLC retention time=2.86 minutes (YMC Combi 4.6×50 mm S-5 ODS column) eluting with 10-90% aqueous methanol+0.2% phosphoric acid over a 4 minute gradient. MS: (M+H)=262.15. 1H NMR (500 MHz, CDCl3) d ppm 3.91 (s, 2H) 4.02 (s, 2H) 7.46-7.53 (m, 2H) 7.69 (d, J=6.6 Hz, 1H).

Provenance & Evidence