Tert-Butylamine → 2-methylpropan-2-aminium (Z)-4-(5-chloro-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl)-4-(4-chloro-2-methylphenyl)but-3-enoate

Participants

Reaction Steps

To a solution of (Z)-methyl 4-(5-chloro-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl)-4-(4-chloro-2-methylphenyl)but-3-enoate (13.34 g, 32.0 mmol) in dioxane (150 mL) was added 2 N aqueous NaOH (32 mL, 64 mmol). The mixture was stirred at rt for about 16 h then partitioned between EtOAc (300 mL) and 10% citric acid (200 mL). The layers were separated and the aqueous layer was extracted with EtOAc (300 mL). The combined organic layers were washed with water (300 mL) followed by brine (300 mL) then concentrated in vacuo. The residue was triturated in Et2O to give (Z)-4-(5-chloro-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl)-4-(4-chloro-2-methylphenyl)but-3-enoic acid (12.31 g, 95%) as an off-white solid: LC-MS (Table 1, Method g) Rt=2.20 min, m/z 402/404 (M+H)+; 1H-NMR (DMSO, Bruker 400 MHz) δ 12.18 (s, 1H), 8.42-8.39 (m, 1H), 7.80-7.68 (m, 2H), 7.26-7.19 (m, 1H), 7.16 (d, J=2.2 Hz, 1H), 7.08-7.04 (m, 1H), 7.01-6.97 (m, 1H), 5.91 (t, J=7.2 Hz, 1H), 3.92 (s, 3H), 2.95 (s, 2H), 2.34 (s, 3H). To a suspension of (Z)-4-(5-chloro-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl)-4-(4-chloro-2-methylphenyl)but-3-enoic acid (12.31 g, 30.6 mmol) in THF (50 mL) was added 2-methylpropan-2-amine (6.46 mL, 61.2 mmol). The mixture was stirred at rt for about 10 min then concentrated in vacuo to give 2-methylpropan-2-aminium (Z)-4-(5-chloro-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl)-4-(4-chloro-2-methylphenyl)but-3-enoate (14.40 g, 95%): LC-MS (Table 1, Method g) Rt=2.20 min, m/z 402/404 (M+H)+; 1H-NMR (DMSO, Bruker 400 MHz) δ 8.41-8.38 (m, 1H), 7.78-7.67 (m, 2H), 7.24-7.17 (m, 1H), 7.13 (d, J=2.1 Hz, 1H), 7.05-7.01 (m, 1H), 6.99-6.96 (m, 1H), 6.01 (t, J=7.1 Hz, 1H), 3.91 (s, 3H), 2.81-2.59 (m, 2H), 2.32 (s, 3H), 1.16 (s, 9H).

Provenance & Evidence