2-Substituted imidazoles. 1. Reactions of 1-methyl-2-(2-furyl)imidazole with electrophiles

1-Methyl-2-(2-furyl)imidazole has been synthesized. Electrophilic attack (bromination, nitration, formylation, acylation, and hydroxymethylation) occurs in most cases at the free -position of the furan ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1396–1400, October, 1989.     

Synthesis and Properties of 2-(2-Furyl)- and 2-(2-Thienyl)-1-methylphenanthro[9,10-d]imidazoles

Condensation of 9,10-phenanthrenequinone with 2-furaldehyde and 2-thiophenecarbaldehyde in glacial acetic acid in the presence of ammonium acetate gave 2-(2-furyl)- and 2-(2-thienyl)phenanthro[9,10-d]imidazoles which were converted into the corresponding 1-methyl derivatives. The furan and thiophene rings in the products lose their acidophobic properties. Depending on the conditions, electrophilic substitution reactions in 2-(2-furyl)- and 2-(2-thienyl)phenanthro[9,10-d]imidazoles occur both at the furan (thiophene) and phenanthrene moieties.     

Investigations of 2-substituted imidazoles. 2. Synthesis and electrophilic substitution of 1-methyl-2-(thienyl-2)imidazole. A convenient method of methylation of 2-R-imidazoles

We have synthesized 2-(thienyl-2)imidazole and its N-methyl derivative. The latter product was obtained by nitration, bromination, acylation, and formylation, occurring as a rule on the thiophene ring. A general method for methylating 2-R-imidazoles with methyl iodide KOH-dimethoxy ethane is proposed.For Communication 1 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1414–1418, October, 1991.     

Research on the chemistry of 2-hetarylbenzimidazole. 3. Reaction of 1-methyl-2-(5′-methyl-2′-hetaryl) benzimidazoles with electrophilic reagents

A number of new derivatives of 1-methyl-2-(5-methyl-2-hetaryl)benzimidazole were synthesized by electrophilic substitution. The substituent enters the position of the 4-hetaryl ring. A furan ring that contains a methyl group in the 5 position undergoes profound destructive oxidation under the influence of acetyl nitrate. Depending on the conditions, bromination leads to the formation of bromo derivatives that are substituted in the benzene or hetaryl ring.See [7] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 520–523, April, 1981.     

Research on the chemistry of 2-hetarylbenzimidazoles. 4. Oxidation of 1-methyl-2-(5′-methyl-2′-hetaryl)benzimidazoles

The methyl group in 1-methyl-2-(5-methyl-2-hetaryl)benzimidazoles (hetaryl = furyl and thienyl) was oxidized. It was found that a salt of a carboxylic acid, which in an acidic medium loses carbon dioxide to give 1-methyl-2-(2-furyl)-benzimidazole, is formed when 1-methy1-2-(5-methyl-2-furyl)benzimidazole is treated with an aqueous solution of potassium permanganate. The carboxy derivative of thiophene is considerably more stable. Oxidation by means of selenium dioxide leads to the corresponding 5-formyl derivative. The structures of the compounds obtained were confirmed by data from the IR and PMR spectra.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1089–1091, August, 1982.     

Chemistry of 2-hetarylbenimidazoles. 7. Transformations of trans-1-methyl-2-[Β-(2′-furyl)vinyl] benzimidazole

Electrophilic substitution reactions in the furylvinylbenzimidazole series were studied. In nitration, sulfonation, bromination, acylation, formylation, and hydroxymethylation reactions, the substituent enters at the -position of the furan ring. The presence of a vinylene group reduces the influence of the benzimidazole fragment on the furan ring, and therefore the reactions in the latter proceed considerably more rapidly and under milder conditions than in the case of furylbenzimidazole. Calculated data are given for the -electronic density on the carbon atoms of furyl-vinylbenzimidazole, obtained by the CNDO method.For Communication 6, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1078–1081, August, 1986.The authors wish to express their gratitude to Yu. N. Sheinker for help in the interpretation of the PMR spectra.     

2-Substituted imidazoles. 3. Metallation of 1-methyl-2-phenyl- and 1-methyl-2-(furyl-2)imidazoles

1-Methyl-2-phenylimidazole reacts with butyllithium to give 5-lithium substituted products. On the other hand, 1-methyl-2-(furyl-2)imidazole is metallated under the same conditions exclusively on the furan ring and primarily in the 3 position. The introduction of triethylamine into the reaction mixture, or replacement of butyllithium by lithium 2,2,6,6-tetramethylpiperidide leads to the formation of a lithium derivative substituted at the 5-position of the furan ring exclusively.For Communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 61–66, January, 1992.