1-(5-Methyl-1H-imidazol-4-yl)ethan-1-one → HCID 178433266, compound

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Reaction Steps

A 3.0 M solution of phenyl-magnesium bromide (1.3 ml, 4 mmol) in ether was added to a solution of 0.25 g (2.0 mmol) 4-acetyl-5-methyl-imidazole in 20 ml dry tetrahydrofuran at ambient temperature. The mixture was refluxed for 2 h. The solvents are evaporated and the organics are extracted twice with ethyl acetate. The combined organic extracts are concentrated and the residue was purified by flash chromatography (silica gel, dichloromethane/methanol 95:5) to yield a product mainly containing 1-(5-methyl-3H-imidazol-4-yl)-1-phenyl-ethanol. This product was dissolved in 20 ml ethanol/ethyl acetate (1:1) and 0.5 ml of 10M hydrochloric acid was added. The mixture was hydrogenated (5% Pd/C, 0.07 g; 4 bar H2, 50° C.) for 4 h. Then the mixture was filtered through Celite®, and the solvent was evaporated. The residue was partitioned between an aqueous solution of potassium carbonate and ethyl acetate. The organic layer was dried over magnesium sulfate and evaporated to yield a yellow oil that was purified by flash chromatography (silica gel, dichloromethane/methanol 95:5). To the amine an equimolar amount of hydrochloric acid in ethanol (5M) was added. By dilution with ether 4-methyl-5-(1-phenyl-ethyl)-1H-imidazole hydrochloride precipitated as a colourless solid that was filtered off (45 mg, 12%); MS (EI): 186.1 (M+.), 171.1 (((M-CH3)+.), 100%).

Provenance & Evidence