反应详情

A solution of ethyl 5-(pyridin-2-yl)-4-vinylisoxazole-3-carboxylate (40 mg, 0.164 mmol) and Pd/C (3.49 mg, 0.033 mmol) in ethanol (3 mL) was placed on Parr Shaker under hydrogen (45 psi) for 5 h. Filtration to remove the catalyst followed by concentration under reduced pressure afforded ethyl 4-ethyl-5-(pyridin-2-yl)isoxazole-3-carboxylate (36.1 mg, 0.147 mmol, 90% yield). The compound had an HPLC retention time=3.13 min.—Column: YMC S5 COMBISCREEN® 4.6×50 mm; Gradient time: 4 min; Flow rate=4 ml/min; Solvent A=10% MeOH—90% Water—0.2% H3PO4; Solvent B=90% MeOH—10% water—0.2% H3PO4; Start % B=0; Final % B=100. LC-MS: M+1 247+. 1H NMR (400 MHz, MeOD) δ ppm 1.23 (t, 3H), 1.43 (t, J=7.15 Hz, 3H), 3.17 (q, J=7.53 Hz, 2H), 4.46 (q, J=7.28 Hz, 2H), 7.46 (ddd, J=7.03, 5.14, 1.63 Hz, 1H), 7.90-8.01 (m, 2H), and 8.73 (dt, J=4.77, 1.38 Hz, 1H).

1. filtrationFiltration
2. customto remove the catalyst
3. concentrationfollowed by concentration under reduced pressure