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0 °C

A suspension of sodium hydride (60% in mineral oil, 122 mg, 3.06 mmol) in THF (10 mL) was cooled to 0° C., and diethyl[(5-bromo-1,3-thiazol-2-yl)methyl]phosphonate (769 mg, 2.448 mmol) in THF (2 mL) was added dropwise and subsequently stirred at 0° C. for 30 minutes. Ethyl 4-oxocyclohexanecarboxylate (417 mg, 2.448 mmol) in THF (2 mL) was then added, and allowed to warm to room temperature over 2 h. Then, the reaction was diluted with saturated ammonium chloride and extracted with ethyl acetate (2×). The combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography on silica gel (0-10% ethyl acetate in hexanes) to afford ethyl 4-[(5-bromo-1,3-thiazol-2-yl)methylidene]cyclohexanecarboxylate as a yellow oil. MS ESI calc'd. for C13H17BrNO2S [M+H]+ 330, 332. found 330, 332. 1H NMR (600 MHz, CDCl3) δ 7.62 (s, 1H), 6.34 (s, 1H), 4.14 (q, J=7.1 Hz, 2H), 3.41-3.33 (m, 1H), 2.60-2.52 (m, 1H), 2.47-2.40 (m, 1H), 2.31-2.19 (m, 2H), 2.12-2.02 (m, 2H), 1.80-1.63 (m, 2H), 1.26 (t, J=7.1 Hz, 3H).

1. temperatureto warm to room temperature over 2 h
2. extractionextracted with ethyl acetate (2×)
3. washThe combined organic layers were washed with brine
4. dry with materialdried over magnesium sulfate
5. concentrationconcentrated under reduced pressure
6. customThe residue was purified by chromatography on silica gel (0-10% ethyl acetate in hexanes)