反应详情

A solution of methyl isobutyrylacetate (1.37 mL, 10.2 mmol) in THF (2.1 mL) was stirred at 0° C. as a 0.5 N solution of sodium methoxide in methanol (20.3 mL, 10.2 mmol) was added. A solution of 2,4-dichloro-N-hydroxy-3-pyridinecarboximidoyl chloride (1.94 g, 8.64 mmol) in THF (19 mL) was added and the resulting solution was allowed to warm to room temperature and stir overnight. The mixture was concentrated and the residue partitioned between ethyl acetate and brine. The organic layer was dried with MgSO4, filtered and concentrated. The residue was purified by chromatography (silica gel, hexanes to 3:7 ethyl acetate:hexanes gradient elution) and fractions containing the product concentrated. The residue was azetroped with methanol then dichloromethane to provide methyl 3-(2,4-dichloro-3-pyridinyl)-5-(1-methylethyl)-4-isoxazolecarboxylate (1.64 g, 66% as 0.15 dichloromethane). 1H NMR (400 MHz, DMSO-d6): δ 8.65 (d, J=5 Hz, 1H), 7.82 (d, J=5 Hz, 1H), 3.79 (septet, J=7 Hz, 1H), 3.63 (s, 3H), 1.34 (m, 6H).

1. additionwas added
2. concentrationThe mixture was concentrated
3. customthe residue partitioned between ethyl acetate and brine
4. dry with materialThe organic layer was dried with MgSO4
5. filtrationfiltered
6. concentrationconcentrated
7. customThe residue was purified by chromatography (silica gel, hexanes to 3:7 ethyl acetate:hexanes gradient elution) and fractions
8. additioncontaining the product
9. concentrationconcentrated