Acetonitrile → 3-(1-Methylcyclopropyl)-3-oxopropanenitrile

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Reaction Steps

Combine lithium diisopropylamide (LDA, 2.0 M/heptanes; Aldrich; 2.2 eq, 88 mmol, 44 mL) with THF (1.5 mL/mmol; 60 mL) and cool to −78° C. Combine methyl 1-methylcyclopropane carboxylate (TCI US; 4.56 g, 40 mmol) and CH3CN (4.20 mL, 80 mmol) in THF (10 mL) and add slowly with stirring. Stir the mixture at −65 to −78° C. for 1 hour, then remove the bath and warm the mixture to room temperature. Concentrate the reaction mixture to a slurry under reduced pressure. Add hexanes (150 mL) to form a precipitate from the slurry. Collect the solid by vacuum filtration and wash with hexanes (2×50 mL). Replace the catch flask with a clean one, and dissolve the solid on the frit in 50 mL 2.5 M HCl and collect in the flask. Rinse with 20 mL 2.5 M HCl followed by 200 mL Et2O. Separate the layers in the filtrate and extract the acidic phase with Et2O (150 mL). Combine the Et2O organic phases, dry with MgSO4, filter and concentrate under reduced pressure to yield 3-(1-Methyl-cyclopropyl)-3-oxo-propionitrile as a clear amber oil (3.58 g, 29.1 mmol, 73%). Use without purification in reaction with tolylhydrazine hydrochloride (5.23 g, 33.0 mmol) and ethanol (2 mL/mmol) at reflux for 20 hr. Cool the reaction mixture to room temperature and concentrate under reduced pressure. Dilute the residue with ethyl acetate (250 mL) and wash with water (2×60 mL), saturated aq. NaHCO3 (60 mL) and saturated aq. sodium chloride (60 mL). Dry the organic phase with MgSO4, filter and concentrate by rotary evaporation. Subject residue to silica gel chromatography eluting with a gradient of ethyl acetate and hexane to provide 5-(1-methyl-cyclopropyl)-2-p-tolyl-2H-pyrazol-3-ylamine (4.2238 g, 18.5 mmol, 46%). LCMS (ES+): m/z=228.2 [M+H].

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