Reaction Steps
(3,5-Dimethoxyphenyl)-(2,2,3,3-tetrafluoro-2,3-dihydrobenzo[1,4]dioxin-5-yl)methanone (0.42 g, 1.13 mmol), cyanomethylphosphonic acid diethyl ester (0.36 ml, 2.26 mmol) in anhydrous THF (10 ml), and lithium bis(trimethylsilyl)amide (1.0 M solution in THF, 2.26 ml, 2.26 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 (5% EtOAc in hexane gradient to 25% EtOAc in hexane in about 30 min.) to give 3-(3,5-dimethoxy-phenyl)-3-(2,2,3,3-tetrafluoro-2,3-dihydro-benzo[1,4]dioxin-5-yl)-acrylonitrile as an oil (0.42 g, 94%): 1HNMR (DMSO-d6) 7.70-7.35 (m, 6H, Ar), 6.86 (s, 0.32H, double bond proton of one isomer), 6.68-6.66 (m, 2H, Ar), 6.53 (d, J=2 Hz, 1.3H, Ar), 6.48 (d, J=1 Hz, 0.7H, Ar), 6.27 (s, 0.62H, double bond proton of the other isomer), 3.74 (s, 6H, 2OCH3); 13C NMR (DMSO-d6) δ 160.7, 160.5, 155.0, 153.8, 138.0, 137.3, 136.7, 133.7, 128.7, 128.7, 127.8, 127.5, 126.8, 126.7, 126.5, 119.5, 119.3, 117.1, 116.9, 106.2, 105.3, 102.5, 101.8, 101.1, 100.6, 55.4, 55.4; Anal. Calcd. For C19H13F4NO4: C, 57.73; H, 3.31; N, 3.54; F, 19.22. Found: C, 57.62; H, 3.34; N, 3.49; F, 19.17.
