Imidazole 4.5- diiodo

Imidazole, 4,5-dibromo-l-methyl-synthesis, S, 399 Imidazole, 4,5-di-t-butyl-synthesis, S, 483 X-ray diffraction, S, 350 Imidazole, 4,5-dichloro-chlorination, S, 398 synthesis, S, 398, 473 Imidazole, 4-(3,4-dichlorophenyl)-nitration, 5, 433 Imidazole, 4,5-dicyano-hydrolysis, S, 435-436 synthesis, S, 461, 472, 487 Imidazole, 4,5-dicyano-1-vinyl-synthesis, S, 387 Imidazole, 4,5-dihydro-mass spectra, 5, 360 Imidazole, 4-(dihydroxybutyl)-synthesis, S, 484 Imidazole, 4,5-diiodo-nitration, S, 396 synthesis, S, 400 Imidazole, 2,4-diiodo-5-methyl-iodination, S, 400 Imidazole, 1,2-dimethyl-anions... 

A synthesis of 5//-pyrrolo[l,2-r] imidazole 105 has been developed via a chemoselective addition/dehydration of acetaldehyde on diiodo imidazole 103 giving the vinylic imidazole 104. This compound, treated under the metathesis condition in the presence of the second-generation Grubbs catalyst, gave the final product 105 (Scheme 11) <2003TL1379>. 

Considerable confusion has existed in the literature since the publication of incorrect structural assignments of 4-iodo- and 4,5-diiodo-imidazoles over 60 years ago (28JPR33). Pauly believed these compounds to be the 2- and 2,4-isomers, respectively, and only recently were the assignments finally corrected (81JOC1781 87AJC1399). Those involved in the field should therefore be wary of many reported structures of bromo- and iodo-imidazoles. For example, 4- (not 2-) iodoimidazole reacted with bromine in chloroform to give 4-bromo-5-iodoimidazole (not the 4-bromo-2-iodo isomer), and there are many other examples (81JOC1781). 

As with other halogenation processes, the monoiodination of imidazole has proved to be a difficult process. A number of recent approaches have shown some success. Thus, imidazoles can be monoiodinated at C-2 via the 2-lithio derivative or Grignard reagent. With iodine and iodic acid 5-chloro-l-methylimidazole was converted to a mixture of 12.8% of the 2,4-diiodo compound and 27.5% of the 4-iodo product. The previously undescribed 2-iodoimidazole (119) has been prepared in low yield by the sequence shown in Eq. (27). ... 

The imidazole, benzoxazole, and benzthiazole derivatives in Table 7-3 are rather moisture-sensitive.92 On the whole, however, the heteroarylstannanes show the same reactions that characterise the homoarylstannanes. With a palladium catalyst, they undergo coupling112 and cross-coupling reactions68 and indeed much of the recent interest in the heteroarylstannanes stems from their applications in the Stille reaction (see Section 22.2). One aspect of this is the synthesis of oligomers and polymers or copolymers, for example by the cross-coupling of 2,5-distannylthiophene with a 1,4-diiodo-arene.113,114... 

Electrophilic nitration can give 4-nitro (and sometimes 4,5-dinitro) products, but if there is a 1-substituent mixtures of 4- and 5-nitro products are formed <80AHC(27)24i>. Reports of direct nitration in the 2-position may not be correct. Nitrodehalogenation is possible, but only at the 4-position <79AJC1727>. A report suggesting that a 2-nitroimidazole was formed when 2,4-diiodo-imidazole was nitrated is flawed because the substrate was in fact 4,5-diiodoimidazole (see Section 3.02.5.3.2) <70CHE614>. 

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