反应详情

To a solution consisting of 5-(3-bromopropyl) thiophene-2-carboxylic acid (from procedure above, 24 g, 78 mmol) in ethyl acetate (150 mL) and methanol (15 mL) at 0° C. was added TMS-diazomethane (50 mL, 100 mmol, 2 M) dropwise over one hour. The reaction mixture was then allowed to warm to room temperature and was stirred for 16 hours, The reaction mixture was concentrated under reduced pressure without workup. The residue was purified by silica gel chromatography. Elution with ethyl acetate-heptane (1:80 v/v) afforded the title compound as a white solid (4.95 g; 24% over two steps); TLC Rf 0.45 (solvent system: 15:85 v/v ethyl acetate-hexanes); MS (ESI+) m/z 263, 265 (isotopic bromines, each (M+H)+); 1HNMR (CDCl3) δ 7.5 (d, 1H), 6.7 (d, 1H), 3.75 (s, 3H), 3.3 (t, 2H), 2.9 (t, 2H), 2.1-2.0 (m, 2H).

1. concentrationThe reaction mixture was concentrated under reduced pressure without workup
2. customThe residue was purified by silica gel chromatography
3. washElution with ethyl acetate-heptane (1:80 v/v)