Reaction Steps
To a solution of sodium tert-butoxide (3.28 g, 34.2 mmol) in tetrahydrofuran (20 mL) at 0° C. was added a solution of methyl 3-methoxyacrylate (2.65 g, 22.8 mmol) and (2-chloro-4-trifluoromethyl-phenyl)-acetonitrile (5.00 g, 22.8 mmol) in tetrahydrofuran (20 mL) dropwise over 45 minutes. The red solution was stirred at 0° C. for 3 hours and then allowed to warm to 10° C. over another 2 hours. The reaction was then treated with 0.2 M aqueous citric acid (50 mL) and extracted with a 2:1 mixture of methyl tert-butyl ether and hexanes (75 mL). The organic layer was washed with an aqueous saturated solution of sodium chloride (50 mL). The organic solution was passed through a short column of silica gel, washing the residual material through the pad with additional methyl tert-butyl ether. The filtrate was concentrated in vacuo to afford 4-(2-chloro-4-trifluoromethyl-phenyl)-4-cyano-but-3-enoic acid methyl ester as a red oil (6.74 g, 97%). Major olefin isomer: 1HNMR (400 MHz, CDCl3) δ 7.71 (s, 1H), 7.58 (d, 1H, J=8.3), 7.49 (d, 1H, J=8.3), 6.89 (t, 1H, J=7.1), 3.78 (s, 3H), 3.69 (d, 2H, J=7.1); 13C NMR (100 MHz, CDCl3) δ 169.4, 145.9, 136.1, 133.7, 133.0 (q, J=33.5), 131.5, 127.6 (q, J=3.8), 124.5 (q, J=3.8), 123.2 (q, J=292), 115.4, 114.7, 52.7, 36.7; IR (ATR, neat) 2957, 2224, 1740, 1438, 1395, 1319, 1268, 1172, 1128, 1080, 1010, 963, 892, 831, 719, 655 cm−1. Minor olefin isomer: 1H-NMR (400 MHz, CDCl3) δ 7.76 (s, 1H), 7.61 (d, 1H, J=7.8), 7.43 (d, 1H, J=7.8), 7.02 (t, 1H, J=7.8), 3.71 (s, 3H), 3.11 (d, 2H, J=7.8).
