Imidazole 2-alkyl-4,5-dicyano

Aldehydes condense with DISN to give 2-alkylimidazoles, but in low yield (73USP37099(X)). A related reaction with ketones produces 2,2-dialkyl-4,5-dicyano-2//-imidazoles. When one alkyl group is methyl and the other is a... 

Syntheses of fused mesoionic heterocycles such as [l,2,3]triazolo[l,5-a]-quinoline, -quinazoline, -quinoxaline, and -benzotriazine derivatives have been described <02T3185>. Cyclizations of alkyl 2-benzoylamino-(4,5-dicyano-1 //-1,2,3-triazol-1 -yl)propenoates gave [1,2,3]triazolo[l, 5-a]pyrazines <02H(56)353>. Reaction of triethyl N-( 1 -ethy 1-2-methy 1-4-nitro-l//-imidazol-5-yl)phosphorimidate with aryl isocyanates provided a route to 2-aryI-2//,4//-imidazo[4,5-fif][l,2,3]triazoles <02JCS(P 1)1968>. 2-(A,A-Diphenylamino)-4-hydrazino-6-... 

If DAMN is mono-N-alkylated before reaction with the carbonyl reagent the method gives 1-alkylimidazoles [15]. For example, 4,5-dicyano-l-(2, 3, 5 -tri-0-benzoyl-)S-D-ribofuranosyl)imidazole (57%) has been made by treatment of the ribosylamino-DAMN with triethyl orthoformate at 90°C in anisole under nitrogen for 5h. The intermediate enamine is not isolated in this case [42]. When DAMN is treated with AyV-dialkylamides in the presence of phosphoryl chloride, the Schiff base (14) (R = NR R ) cyclizes to give 2-dialkylaminoimidazoles (15) (R = NR R ), including 4,5-dicyanoimidazole (15) (R = H) when DMF is used [15], Imidazoles (15) (R = OR, NR R ) can be made in one step when DAMN reacts with orthoesters or iminoether hydrochlorides. Under mild reaction conditions the intermediate alkoxyimines (14) (R = OR" ) or amidines (14) (R = NR R ) can be isolated before oxidation to (15) [46, 47, 49], Table 2.1.4 lists some examples. 

The imidatc (27) reacts at 100°C with excess triethyl orthoformate to give 4,5-dicyano-l-ethylimidazole after vacuum distillation. The reaction becomes economically competitive with other reactions which alkylate 4,5-dicyanoimidazole since the 1-alkyl-4,5-dicyanoimidazoles can be made in one-pot reactions merely by heating DAMN at 100°C with excess ortho ester. No co-solvent is necessary. Presumably, (27) forms first, then 4,5-dicyanoimidazole, then the 1-alkyl derivative, with the anion of 4,5-dicyanoimidazole probably being the reactive species. Imidazole itself is not N-alkylatcd by ortho esters instead it induces alkoxidc displacement to give amide acetals [34]. 

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