Benzimidazolium salts synthesis

The most common way to prepare N-heterocyclic carbenes is the deprotonation of the corresponding azolium salts, like imidazolium, triazolium, tetrazolium, pyrazolium, benzimidazolium, oxazolium or thiazolium salts or their partly saturated pendants, with the help of suitable bases. The pJCa value of imidazolium and benzimidazolium salts was determined to be between 21 and 24, which puts them right in between the neutral carbonyl carbon acids acetone and ethyl acetate [41,42], Arguably, imidazolium-based carbenes have proven to be especially versatile and useful and their synthesis should be discussed in more detail. The synthesis of imidazolium salts has been developed over many decades and numerous powerful methods exist [43]. 

Figure 4.20 Synthesis of phenoxy functionalised benzimidazolium salts and theirpalladium(ll) complexes.

Puterov, Z. KrutoSikov A. Lycka, A. Durcekova, T. (2004). Reactions of Substituted Furan-2-carboxaldehydes and Furo[b]pyrrole Typie Aldehydes with Benzothiazolium Salts. Molecules. Vol. 9, No. 4, pp. 241-255, ISSN. 1420-3049 Riemer, B. Liebscher, J. (1993). Synthesis of Pyrimido[2,l-b]benzoxazolium, Pyrimido[2,l-bjbenzothiazolium and Pyrimido[l,2-a]benzimidazolium Salts by Reaction of 3-Isothiocyanato-2-propeniminium Salts with o-Functionalized Anilines. Synthesis. Vol. 1993, No. 1, pp. 75-76, ISSN. 0039-7881... 

Iqbal MA, Haque RA, Ahamed MBK, Majid AMSA, Al-Raw SS. Synthesis and anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective Ag(I) N-heterocychc carbene complexes. Med Chem Res. 2013 22 2455-2466. 

Azolium salts, for example, imidazolium, triazolium, tetrazolium, pyrazolium, benzimidazolium, oxazolium, and thiazolium, are mostly used as precursors for the synthesis of NHCs (Scheme 2.152). The acidic hydrogen at C2 can be removed by the effect of a base. In a typical approach disclosed by the Arduengo group, the... 

Klimiva, N.V. Galushina, T.S. Avdjunina, N.I. Pjatin, B.M. Fadeeva, T.A. Synthesis and the immimotropic properties of the adamantyl substituted salts of benzimidazolium. The international scientific and technical conference Advances of Chemistry and Applications ofAlicyclic Compounds p. 157, Russia - Samara 1-4 of June, 2004. 

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