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2,4,5-Trimethylimidazole, reaction

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-... [Pg.156]

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). [Pg.11]

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... [Pg.150]

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... [Pg.5773]

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... [Pg.376]

Another major compound, 2,4,5-trimethylimidazole, was also presented in the gas chromatogram (4.15% of peak area of the total volatiles). Shibamoto (//) showed that 2,4,5-trimethyliinidazole was the major product of the reaction of diacetyl and ammonium hydroxide at 100 °C for 180 minutes. Formation mechanism might be similar to those of oxazoles and thiazoles with NH3 replacing H2O or H2S (Figure 6). [Pg.115]

A novel route for the generation of trialkylboron-carbene complexes has been reported (34). As summarized in Scheme 4, the intial step of the reaction sequence involves the N-complexation of 1,4,5-trimethylimidazole 38 with BEts to form 39, followed by deprotonation and rearrangement of resulting ionic species to 40. The final step involves methylation with Mel to form the desired triethylboron-carbene complex, 41. Compound 41 was characterized by mass spectroscopy and H-, C-, and B NMR spectroscopy the B NMR chemical shift for 41 S -12.6) appears in the tetracoordinate boron region. The 1,4,5-trimethylimidazole 38 is also the source of an unusual boryl-borane compound, 43 (34). Treatment with BH3 thf, followed by deprotonation with "BuLi, resulted in the formation of the ionic carbene/borane complex, 42. In turn, 43 was produced via the addition of chlorobis(dimethylamino)borane to 42. Compound 43 exhibits B NMR chemical shifts at S -21.8 (BH3) and 8 27.8 (BNMe2). In related work, N-methyl-AT-borane complexes 44 and 45 have been de-... [Pg.13]

An improvement in the Ru-catalysed hydroformylation of olefins with formates has been attained by employing imidazole derivatives as ligands. Thus, the reaction of terminal olefins R CH=CH2 with HCOjR, catalysed by Ru3(CO)j2 and carried out in the presence of l-phenyl-2,4,5-trimethylimidazole (but in the absence of CO atmosphere), has been found to afford mixtures of hnear (R CH2CH2C02R ) and branched (R CH(Me)C02R ) products but with poor regioselectivity. ... [Pg.357]


See other pages where 2,4,5-Trimethylimidazole, reaction is mentioned: [Pg.430]    [Pg.35]    [Pg.140]    [Pg.395]    [Pg.176]    [Pg.399]    [Pg.456]    [Pg.476]    [Pg.399]    [Pg.456]    [Pg.476]    [Pg.187]    [Pg.271]    [Pg.150]    [Pg.1997]   


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