反应详情

温度

0 °C

To concentrated sulfuric acid (102 mL) was added 1-cyano-cyclopropanecarboxylic acid ethyl ester (60 g, 0.43 mol) dropwise followed by 2-methylpentan-2,4-diol (52 g, 0.44 mmol) dropwise at 0° C. The mixture was stirred for an additional 1 h at 0° C. then poured onto ice-water. The aqueous phase was washed with AcOEt (3×200 mL) and then basified to pH 12 with 10 M NaOH. The resulting mixture was extracted with EtOAc (3×500 mL). The combined organic layer was washed with brine, dried over Na2SO4 and concentrated. The residue was purified by column chromatography on silica gel to give 1-(4,4,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-cyclopropanecarboxylic acid ethyl ester (65 g, yield: 63.2%). 1H NMR (CDCl3 400 MHz): δ4.21-4.06 (m, 3H), 1.73-1.69 (m, 1H), 1.40-1.10 (m, 17H).

1. additionthen poured onto ice-water
2. washThe aqueous phase was washed with AcOEt (3×200 mL)
3. extractionThe resulting mixture was extracted with EtOAc (3×500 mL)
4. washThe combined organic layer was washed with brine
5. dry with materialdried over Na2SO4
6. concentrationconcentrated
7. customThe residue was purified by column chromatography on silica gel