Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester → HCID 11334330, compound

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Reaction Steps

A solution of 6-bromo-3-pyridinecarboxaldehyde (3.06 g, 15.63 mmol) and (carbethoxymethylene)triphenylphosphorane (6.60 g, 17.97 mmol) in toluene (45 mL) was heated at reflux overnight and then cooled to room temperature. After solvent removal at reduced pressure, the residue was chromatographed (16% EtOAc/hexane) to give 3.9 g (97%) of ethyl(E)-3-(6-bromo-3-pyridinyl)-2-propenoate as a pale-yellow solid. Recrystallization from hexane yielded 3.5 g (87%) of pure E-isomer as a white solid, mp 79-80° C. By comparison, the material prepared by the literature method (van den Heuvel, M., et al., J. Org. Chem., 2004, 69, 250-262) had a melting point of 83.6-84.1° C. IR 2979, 1709, 1462, 1179 cm−1; 1H NMR (CDCl3) δ 1.36 (t, J=7.2 Hz, 3H, OCH2CH3), 4.31 (q, J=7.2 Hz, 2H, OCH2CH3), 6.53 (d, J=16.2 Hz, 1H, CH═CHCO), 7.55 (d, J=8.1 Hz, 1H, 5-ArH), 7.68 (d, J=16.2 Hz, 1H, CH═CHCO), 7.72 (dd, J=2.1 Hz, 8.1 Hz, 1H, 4-ArH), 8.52 ppm (d, J=2.1 Hz, 1H, 2-ArH).

Provenance & Evidence