Diethyl (cyanomethyl)phosphonate → 3-(2,5-Dimethoxy-phenyl)-3-(3,5-dimethoxy-phenyl)-acrylonitrile

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Reaction Steps

(2,5-dimethoxyphenyl)-(3,5-dimethoxyphenyl)methanone (0.92 g, 3.04 mmol), cyanomethylphosphonic acid diethyl ester (0.96 ml, 6.09 mmol) in anhydrous THF (15 ml), and lithium bis (trimethylsilyl)amide (1.0 M solution in THF, 6.09 ml, 6.09 mmol) were treated in the same manner as described above for the synthesis of 3-(2,3-dihydrobenzo[1,4]dioxin-6-yl)-3-(3,5-dimethoxyphenyl)acrylonitrile. The crude material was purified via flash column chromatography (10% EtOAc in hexane gradient to 25% EtOAc in hexane in about 20 min.) to give a brown oil, which was lyophilized to give 3-(2,5-dimethoxy-phenyl)-3-(3,5-dimethoxy-phenyl)-acrylonitrile as a light yellow solid (0.88 g, 89%): δ 1HNMR (CDCl3) δ 6.94-6.43 (m, 12H, Ar), 5.89 (s, 0.65H, double proton of one isomer), 5.87 (s, 0.84H, double proton of the other isomer), 3.83-3.67 (multiple singlets, 24H, 8OCH3). The product was a mixture of two isomers with the ratio of 43.6%:56.4%; 13C NMR (CDCl3) δ 161.0, 160.7, 159.9, 159.8, 153.6, 153.5, 151.9, 151.2, 140.3, 140.0, 128.9, 126.9, 117.9, 117.5, 117.3, 116.3, 116.2, 115.8, 113.2, 107.0, 105.8, 102.0, 102.0, 98.3, 97.4, 56.5, 56.0, 56.0, 55.6, 55.6; Anal. Calcd. For C19H19NO4: C, 70.14; H, 5.89; N, 4.30. Found: C, 69.78; H, 5.77; N, 4.20.

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