Diisopropylethylamine → Methyl 1-(methylcarbamoyl)cyclopropane-1-carboxylate

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Reaction Steps

1-(Methoxycarbonyl)cyclopropanecarboxylic acid 5a (2.5 g, 13.9 mmol, prepared by a known method disclosed in “Tetrahedron Letters, 1987, 28 (36), 4225-4228”) was dissolved in 20 mL of N,N-dimethylformamide, followed by addition of methylamine hydrochloride (1.4 g, 20.8 mmol), N,N-diisopropylethylamine (5.4 g, 41.7 mmol) and 2-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (7.9 g, 20.8 mmol), and then the reaction solution was stirred for 3 h. 50 mL of saturated sodium bicarbonate solution were added, and the reaction solution was extracted with ethyl acetate (40 mL×3). The organic phases were combined, washed with saturated sodium bicarbonate solution, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography with elution system A to obtain the title product methyl 1-(methylcarbamoyl)cyclopropanecarboxylate 5b (700 mg, a colorless oil) in 32% yield.

Provenance & Evidence