Dicyano-l-methylimidazole

A mixture of DAMN (100 g, 0.925 mol) and trimethyl orthoformate (350 ml, 3.20 mol) is stirred and heated under partial reflux through a 25 cm Vigreux distillation column. Around 200 ml of distillate, mainly methanol and methyl formate, is collected, b.p. 50-70°C, over 140 min. The distillation temperature is allowed to rise to 102°C, and distillate is slowly collected over 2h (the pot temperature is 115°C). The fractionating column is removed, and the bulk of the remaining ortho ester is distilled off. The residue is distilled 

Hydrazine hydrate (0.39 g, 0.38 ml, 7.72 mmol) is added at room temperature to a suspension of (27) (1.27g, 7.72 mmol) in dry dioxane (8 ml). An immediate and slightly exothermic reaction gives a yellow solution, from which the product precipitates as yellow needles. Filtration, washing with diethyl ether, and drying in vacuo gives (29) (1.13 g, 98%), m.p. 3(X)°C (dec.). 

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Careful choice of reaction conditions also allows 2-lithiation of imidazoles even in the presence of groups susceptible to attack by the reagent. At -100°C in THF 4,5-dicyano-l-methylimidazole forms the 2-lithio compound at -80°C butyllithium attacks one of the nitrile functions (92JHC1091). 1-Alkoxyimidazoles are lithiated by n-butyllithium (THF, -78°C) at the 2-position (98JOC12). 

When 2-bromo-4,5-dicyano-l-methylimidazole is treated at reflux with 4-dimethylaminopyridine the initial nucleophilic substitution product loses its iV-methyl group because 4,5-dicyanoimidazole anions are such good leaving groups (Scheme 36) <89H(29)I325>. 

Condensation of diiminosuccinonitrile (10) with 3-methylbutan-2-one gave 5,6-dicyano-2,2,3-trimethyl-l,2-dihydropyrazine (II) (11%) and 4,5-dicyano-l-isopropyl-2-methylimidazole (7.6%) (383). Cyclization of a-cyanoalkyldiamino-maleonitiiles (12, e.g., R = Me) with phosphorus pentoxide in refluxing ethanol has been shown to give 5,6-dicyano-3-hydroxy(-2-substituted)-l, 2-dihydropyrazines(I3, e.g., R = Me) (489, 490) and the conversion of benzylidenediaminomaleonitrile to 5-carbamoyl-6-cyano- and 6-carbamoyl-5-cyano-2,3-diphenyl-l, 2-dihydropyrazines has been described in Section II.3 (395a). 

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