反应详情

Methyl isobutyrate and ethylenediamine in a molar ratio of 1:3 were heated in a closed pressure vessel at 100° for 62 hrs. The mixture was cooled, clarified by filtration, and the excess ethylenediamine removed from the filtrate by distillation in vacuo. The residue was distilled, boiling point 115°-117°/0.9 mm Hg to yield N-isobutyrylethylenediamine whose identity was confirmed by examination of the NMR and IR spectra. The latter, 15 g., was suspended in 200 ml. of dry THF and a solution of 20 g. (ca. 0.5 mole) of lithium aluminum hydride in 200 ml. of dry THF was added dropwise. The mixture was refluxed for 23 hrs., the excess lithium aluminum hydride destroyed by hydrolysis. The insoluble material was removed by filtration, and the filtrate concentrated in vacuo to yield N-(2-methylpropyl)ethylenediamine as an oil, yield 37 g. The identity of the product was confirmed by examination of the NMR spectrum, and 5.8 g. (0.05 mole) thereof was then dissolved in 20 ml. of MeOH and a solution of 5.8 g. (0.055 mole) of cyanogen bromide in MeOH was added in dropwise fashion with cooling. The mixture was stirred for 1/2 hr. and then concentrated in vacuo to an oil. The latter was dissolved in methylene chloride and again concentrated in vacuo to aid in removal of last traces of MeOH. The NMR spectrum of the residue, an oil, confirmed the structure 1-(2-methylpropyl)-1H-imidazo-2-amine hydrobromide. This material was then condensed with ethyl oximinocyanoacetate substantially according to the method described in Procedure 1. The product was recovered by distillation of the solvent from the reaction mixture in vacuo. The residue was dissolved in water and acidified with acetic acid. The precipitate that formed was collected and air dried. The damp solid was recrystallized from methanol/ethanol, m.p. 242.5°-243.5° d.

1. temperatureThe mixture was cooled
2. filtrationclarified by filtration
3. customthe excess ethylenediamine removed from the filtrate by distillation in vacuo
4. distillationThe residue was distilled