Triethylamine → tert-butyl 3-(1-benzyl-1H-pyrazol-4-yl)-5,6-dihydropyridine-1(2H)-carboxylate

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Reaction Steps

A 250-mL 3-necked round-bottomed flask was charged with a solution of tert-butyl 3-(trifluoromethylsulfonyloxy)-5,6-dihydropyridine-1(2H)-carboxylate (5.0 g, 15.11 mmol, 1.00 equiv) in toluene (100 mL), a solution of 1-benzyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (4.29 g, 15.11 mmol, 1.00 equiv) in ethanol (100 mL), triethylamine (4.58 g, 45.35 mmol, 3.00 equiv), Pd(PPh3)4 (345 mg, 0.30 mmol, 0.01 equiv) and water (30 mL). The resulting mixture was heated to reflux for 3 hours. Upon completion, the mixture was diluted with water (100 mL). Then, it was extracted with ethyl acetate (3×200 mL). Combined organic layers were dried over anhydrous sodium sulfate and concentrated on a rotary evaporator. The residue was purified by silica gel column chromatography eluted with ethyl acetate/petroleum ether (1:5) affording tert-butyl 3-(1-benzyl-1H-pyrazol-4-yl)-5,6-dihydropyridine-1(2H)-carboxylate as yellow oil (5.0 g, 98%).

Provenance & Evidence