[S:1]1[CH:5]=[CH:4][C:3]([CH:6]=O)=[C:2]1[CH:8]=O.COP([CH:16]([NH:20]C(=O)C)[C:17](=[O:19])[CH3:18])(=O)OC.C1CCN2C(=NCCC2)CC1>ClCCl>[S:1]1[C:2]2=[CH:8][N:20]=[C:16]([C:17](=[O:19])[CH3:18])[CH:6]=[C:3]2[CH:4]=[CH:5]1A solution of 2,3-thiophenedicarboxaldehyde (600 mg, 4.28 mmol) in dichloromethane (50 ml) was cooled to 0° C. under an atmosphere of nitrogen. (1-Acetylamino-2-oxo-propyl)-phosphonic acid dimethyl ester (1.05 g, 4.70 mmol) was added [literature procedure: Kitamura, et al. Tet. Lett., 36(32), 1995, pp. 5769-5772], followed by DBU (0.471 ml, 4.70 mmol), and the mixture allowed to warm to ambient temperature overnight, then concentrated in vacuo, and the residue was then purified by flash chromatography (0-50% ethyl acetate in hexanes) to provide 1-thieno[2,3-c]pyridin-5-yl-ethanone as a white solid (326 mg, 43%). 1HNMR (250 MHz, CDCl3): δ 9.20 (s, 1H), 8.50 (d, 1H, J=1.02), 7.80 (d, 1H, J=5.36), 7.51 (d, 1H, J=5.36), 2.81 (s, 3H).
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