Reaction Steps
2-Fluoro-2-methylpropyl trifluoromethanesulfonate (obtained as described in Example 1, preparation of starting materials) (389 mg, 1.73 mmol) was added to a solution of (E)-methyl 3-(4-(3,3-dimethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylate (racemate) (obtained as described in Example 7, preparation of starting materials) (250 mg, 0.69 mmol) and N,N-diisopropylethylamine (0.453 ml, 2.60 mmol) in 1,4-dioxane (1.25 ml). The mixture was stirred at 95° for 64 hours and then partitioned between DCM (30 ml) and water (30 ml). The aqueous layer was extracted with DCM (20 ml) and the extracts combined with the organic layer. The combined extracts were filtered through a phase-separating paper and evaporated. The residue was purified by flash silica chromatography, elution solvent 153% EtOAc in heptane. Pure fractions were evaporated to dryness to afford (E)-methyl 3-(4-(2-(2-fluoro-2-methylpropyl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylate (racemate) (178 mg, 59.1%) as a beige solid. The racemic product was purified by preparative HPLC (Chiralpak AD column, 20 μm silica, 50 mm diameter, 250 mm length), Heptane:Ethanol: 80:20. Fractions containing the desired compounds were evaporated to dryness to afford (E)-methyl 3-(4-(2-(2-fluoro-2-methylpropyl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylate (isomer 1, first eluted, 70 mg) and (E)-methyl 3-(4-(2-(2-fluoro-2-methylpropyl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylate (isomer 2, second eluted, 66 mg). 1H NMR (400 MHz, CDCl3, 30° C.) δ 1.00 (3H, s), 1.13 (3H, d), 1.20 (3H, s), 1.44 (3H, d), 2.57-2.78 (3H, m), 2.93 (1H, dd), 3.80 (3H, s), 5.05 (1H, s), 6.41 (1H, d), 7.13 (1H, ddd), 7.18 (1H, ddd), 7.32 (1H, d), 7.43 (2H, d), 7.51 (2H, d), 7.54 (1H, d), 7.64 (1, s), 7.67 (1H d). m/z: ES+ [M+H]+ 435.
