A mixture of 3-bromo-2-methoxy-5-methyl-7-(trifluoroacetyl)-6,7,8,9-tetrahydro -5H-pyrido[2,3-d]azepine (220 mg, 599 μmol), Bu3SnCH═CH2 (523 μl, 1.79 mmol), Pd(PPh3)4 (50 mg), and toluene (10 ml) was heated in a sealed tube at 110° C. for 16 h. The solvent was evaporated and the resulting residue was purified by column chromatography to render 165 mg (88%) of 2-methoxy-5-methyl-7-(trifluoroacetyl)-3-vinyl-6,7,8,9-tetrahydro-5H-pyrido[2,3-d]azepine. A mixture of 2-methoxy-5-methyl-7-(trifluoroacetyl)-3-vinyl-6,7,8,9-tetrahydro-5H-pyrido[2,3-d]azepine (32 mg, 102 μmol), K2CO3 (40 mg), MeOH (5 ml) and H2O (1 ml) was heated to reflux for 10 min. The reaction mixture was concentrated in vacuo and the resulting residue was purified by column chromatography to yield 17.0 mg (77%) of 2-methoxy-5-methyl-3-vinyl-6,7,8,9-tetrahydro-5H-pyrido[2,3-d]azepine. 1H-NMR (CDCl3) δ 7.58 (s, 1H), 6.92 (dd, 1H), 5.86 (d, 1H), 5.40 (d, 1H), 4.02 (s, 3H), 3.60-3.40 (m, 4H), 3.31 (m, 1H), 3.18 (dd, 1H), 3.00 (m, 1H), 1.52 (d, 3H) ppm.
