Acetic Acid → tert-Butyl (2-{[4-(1-{1,3-dimethyl-1H-pyrazol-4-ylmethyl}piperidin-4-yl)benzoyl]amino}phenyl)carbamate

Participants

Reaction Steps

tert-Butyl 2-[(4-piperidin-4-ylbenzoyl)amino]phenylcarbamate (6.83 g, 17.3 mmol) and 1,3-dimethyl-1H-pyrazole-4-carbaldehyde (3.0 g, 24.2 mmol) were dissolved in dichloromethane (150 ml). Acetic acid (996 μl, 17.3 mmol) was then added and the reaction mixture allowed to stir at room temperature for four hours. Sodium triacetoxyborohydride (5.49 g, 25.9 mmol) was then added and reaction mixture stirred for a further 18 hours. Saturated aqueous sodium bicarbonate solution (300 ml) was then carefully added followed by dichloromethane (100 ml). The organic layer was separated and the aqueous layer re-extracted with more dichloromethane (150 ml). The combined organic extracts were dried over magnesium sulphate, filtered and evaporated to dryness. The residue obtained was purified by flash chromatography on silica, eluting with a 5% (v/v) solution of methanol in dichloromethane followed by a rising gradient of 5-10% (v/v) methanol in dichloromethane to afford a clear gum, which was taken up in diethyl ether and evaporated to dryness to afford the title compound (7.61 g, 87%); NMR Spectrum: (DMSO d6) δ 1.43 (s, 9H), 1.69 (m, 4H), 1.98 (m, 2H), 2.10 (s, 3H), 2.56 (m, 1H), 2.92 (m, 2H), 3.26 (s, 2H), 3.70 (s, 3H), 7.15 (m, 2H), 7.40 (m, 3H), 7.52 (m, 2H), 7.87 (d, 2H), 8.60 (s, 1H), 9.73 (s, 1H); Mass Spectrum: M+H+ 504.

Provenance & Evidence