Imidazole dimerization

Yan, S. and Bu, Y. (2005) Coupling properties of imidazole dimer radical cation assisted by embedded water molecule toward understanding of interaction character of hydrogen-bonded histidine residue side-chains, J. Chem. Phys. 122, 184324. 

Fig. 9.7 Representative acyclic and cyclic pyrrole-imidazole dimers...

For this, Guthrie s group is planning to synthesize a steroid-imidazole dimer by combining two ketone analogues with an aromatic diamine. 

Atsushi, K., Atsuhiro, T., Takeru, H., Toyoji, O., and Jiro, A. (2010) Fast photochromic polymers carrying [2.2] paracyclophane-bridged imidazole dimer. Macromaiecules, 43, 3764-3769. 

Unfortunately, only patents issued after 1975 can be searched electronically and searching for chemical structures is complicated by the fact that trivial names abound. In compiling a database for HABIs, I found different patents which identified lophine dimers, imidazole dimers, imidazolyl dimers, DYLUX , bisimidazoles, biimidazoles, etc. 

Imidazoles and pyrazoles with free NH groups form hydrogen-bonded dimers and oligomers (66AHC(6)347). 

Tetraazafulvalenes bearing two pyrazole subunits could be prepared by an original way. Tlius, treatment of benzylidene acetophenone with iso-pentylnitrite leads to an A, A -dihydroxy-bipyrazolyl-A, A -oxide, which in turn can be oxidized to TAF of type 100 (72CC961, 79JOC3211). Another type of oxidative dimerization was observed by the reaction of the electron-rich l-methyl-2,4-bis(dimethylamino)imidazole with silver salts (83TL3563). A bis-cation was isolated in 30% yield in the presence of sodium tetrafluo-roborate an unsymmetrical structure 101 was predicted from its NMR data (Scheme 40). 

On carbonylation in methylene chloride it undergoes the substitution of the diene ligands, rearrangement, and cis-trans isomerization to yield 64 (97JOM(530) 259). l,r-(l,2-Ethylene)-3,3 -imidazol-2,2 -diylidene and the dimer [(T -cod)Rh (ir-Cl)] form the dinuclear species 65. 

Dervan. Cooperative hairpin dimers for recognition of DNA by pyrrole-imidazole polyamides. Angew. Chem.-Int. Edit. 1998,... 

Because silylation with HMDS 2/TCS 14 in acetonitrile at ambient temperature converts the unreactive a-chloroketone moiety of 743 into an /Z-mixture of reactive alkyl 4-chloro-3-trimethylsilyloxycrotonates 746a, b [230, 231] which can be isolated and distilled, if humidity is excluded, silylation of 743a, b in the presence of ami dine salts such as 745 gives the desired ethyl or methyl imidazole(4,5)-acetates 748a, b via IMz and 747b. The reaction of formamidine acetate with 746a,b affords 745 (with R=H) in up to 70% yield [232, 233] (Scheme 5.79). As side reactions one must, e.g., take into account the reaction of 746 with ammonia to give 755 which subsequently dimerizes to the pyrazine 756, as discussed in Section 5.5.3. 

Yang Q, Khvostichenko D, Atkinson J, Boulatov R. 2008. Simple dimer containing dissocia-tively stable mono-imidazole ligated ferrohemes. Chem Commun (8) 963. 

More recently 233) it has been reported that cross-linked polystyrene containing imidazole ligands did not provide a support rigid enough to prevent dimerization, and that the p-oxo dimer was benzene extracted from oxygenated tetraphenyl porphyrin iron(ll), Fe(TPP), which had been attached to the modified polystyrene. A discussion of model synthetic porphyrins, from which definitive structural and other physical data are obtained, is given in section V.C. 

Fig. 13. Cooperative closed dimers assembled from imidazole-functionalized porphyrins.

Attempts have been made to prepare aminoisocyanates from suitable hydrazidocarbo-nylimidazoles. However, because of the high reactivity of the expected product, a dimerization occurred instead, as illustrated by the thermolysis of imidazole-A-carboxylic acid (l,l-pentamethylene)hydrazide.[17]... 

Neutral complexes with azolate ligands of the type [AuL(PPh3)], with L representing differently substituted pyrazolates,2251,2366 imidazolates,365,2 69 2370 benzidimidazolates, 71 2372 triazolate,2373 tetraazolate (403),536 or 2,2 -bibenzimidazolates (404),2374,2375 have been prepared. The structure of the [Au(l,2,4-triaz)(PPh3)] is a dimer with Au-,Au interactions (405).23 3 The antimicrobial... 

The biphenyl ligand functionalized with two imidazoles (6) was used to produce distorted tetrahedral complexes of zinc.119 2,2 -Biimidazole can act as a bidentate ligand coordinating to one zinc ion (7) or as a bridging ligand in the formation of dimeric species (8) with X-ray structures of both binding motifs.120... 

Diethylenetriamineacetic acid has been used in the formation of homodinuclear zinc complexes with the bridging imidazole. The crystal structure of [LZn(imidazolate)ZnL]C104 was obtained. The magnetics of the heterodinuclear Cu-Zn complex were studied and single crystal EPR of the Zn2 dimer doped with the CuZn dimer.139... 

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