2,4,5-Trimethylimidazole

Reaction of trisubstituted imidazole N-oxides such as l,4,5-trimethylimidazole-3-oxide 930 with 18/NEt3 in CH2CI2 at 0-5 °C affords the l,4,5-trimethyl-2-cyano-... 

Photorearrangement has been observed in certain pyrazoles. N- and (7-alkylated pyrazoles (158) are converted into imidazoles (159) by interchange of the N-2 and C-3 atoms.142 1,4,5-Trimethylimidazole (160) itself undergoes rearrangement to the alternative 1,2,5-tri-methylimidazole (161),143 presumably by a different pathway. 

The nitration of l,4,5-trimethylimidazole-3-oxide and l-methylpyrazole-2-oxide may also occur at about the encounter rate (Ferguson et al., 1977). 

The nitration of 1,4,5-trimethylimidazole 3-oxide with the sulfuric-nitric acid mixture leads to the 2-nitro derivative [76, 162], Both this compound and 1-meth-ylpyrazole 2-oxide enter into reaction in the form of the free base [76], The nitration of 2-aryl-1-hydroxyimidazole 3-oxides leads either to cleavage of the imidazole ring or to the formation of the 4-nitro or 4,5-dinitro derivatives, depending on the reaction conditions [162] (Scheme 15). 

Recent Japanese patents158 relate to the preparation of 2,4,5-trimethylimidazole (and other U-substituted imidazoles) when 3-aminobut-l-yne is refluxed for 5 hours with acetamide. 3-Butynyl-thiourea (39) and 3-butynylurea are converted by concentrated sulfuric acid into 4,5-dimethylimidazole-2-thione (40) and 4,5-dimethyl-2-imidazolone, respectively. The latter compound is also... 

Nuclear magnetic resonance spectroscopy has been used to determine product ratios from photoisomerization reactions of 1,4,5-trimethylimidazole,227 to determine substituent positions,228-231 and, in general, to study structural problems.123,124,138-139,217, 231-240 Studies of NMR spectra of the halogenation products of imidazoles show that the 4-halogenated compound is formed initially.230... 

Trialky Iboron carbene adducts have been prepared via a novel synthetic route, as shown in Scheme b. The initial first step involves reaction of BEt3 with 1,4,5-trimethylimidazole (56) to afford the BEts adduct (57), followed by deprotonation and rearrangement to give an ionic species (58). The triethyl-boron carbene adduct is generated in the final step by way of... 

Although the reverse reaction is well known, the photochemical conversion of imidazoles into pyrazoles and benzimidazoles into indazoles does not take place. However, 1,4- and 1,2-disubstituted imidazoles are interconverted in f-butanol, while 1,4,5-trimethylimidazole gives the 1,2,5-isomer (40%) in ethanol, f-butanol or cyclohexane. In the last-named... 

The mass spectrum of I-methyl-4-nitroimidazole-5-carboxylic acid amide shows the elimination of water by an electron impact as distinct from the usual thermal process. In l,4,5-trimethylimidazole-2-carboxylic acid the principal loss is that of CO2. Subsequent loss of O, OH, and HCN was also observed (Schofield et al., p. 173). Ferguson and Schofield (pp. 172,173) have reported considerable data for imidazole JV-oxides. Thus 1-methoxy-4,5-dimethyl-2-phenylimidazole (which loses OCH3 and CH3CN from the fragment m/e 171) is readily distinguished from l,4,5-trimethyl-2-phenyl-imidazole 3-oxide (loss of O and OH). The spectra of 1-benzylimidazoles are dominated by the tropylium ion. ... 

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