Triethylamine → (Z)-Methyl 3-(4-amino-3,5-dimethylphenyl)-2-(benzyloxycarbonyl)acrylate

Participants

Reaction Steps

A 2 L round bottom flask was charged 4-iodo-2,6-dimethylbenzenamine hydrochloride salt (55 g, 194 mmol), methyl 2-(benzyloxycarbonyl)acrylate (59.2 g, 252 mmol), tetrabutylammonium chloride (59.2 g, 213 mmol), palladium (II) acetate (4.34 g, 19.4 mmol), and tetrahydrofuran (1.2 L, degassed by a flow of nitrogen for 30 min). The mixture was stirred so that a suspension was formed and then degassed by a flow of nitrogen for 30 min. Triethylamine (10 mL, 789 mmol) was added and the resulting mixture was heated at reflux for 3 h. After cooling to room temperature, the reaction mixture was filtered through a pad of celite, washed with tetrahydrofuran (2×100 mL), and concentrated. The residue was dissolved in dichloromethane, washed with water (3×) and brine (2×), dried over sodium sulfate, and concentrated. Flash chromatography (silica gel using 1:9 ethyl acetate/dichloromethane) gave a tan solid. The solid was recrystallized from warm methanol (210 mL) and water (100 mL). The mixture was held at room temperature overnight, then at 0° C. for 2 h, and finally at −15° C. for 2 h. The resulting solid was filtered, washed with ice cold 1:1 methanol/water, and dried under high vacuum overnight to give 44.7 g (65%) as a light tan solid which was a mixture of Z/E isomers (73:27). 1H-NMR (DMSO-d6) δ, 2.05 (s, 6H), 3.61 (s, 0.8H), 3.68 (s, 2.2H), 5.00 (s, 0.54H), 5.13 (s, 1.46H), 5.24 (s, 2H), 7.40-7.21 (m, 8H), 8.51 (s, 0.27H), 8.79 (s, 0.73H); 13C-NMR (DMSO-d6) δ 17.8, 51.7, 65.3, 119.4, 120.0, 120.3, 127.3, 127.7, 128.3, 130.9, 135.8, 137.2, 146.9, 154.7, 166.0.

Provenance & Evidence