Benzimidazolium triflate

Form Supplied in colorless crystals not commercially available. 

Preparative Methods TfOH (1.0 equiv) is added to benzimidazole (1.0 equiv) in dichloromethane at 0 °C, followed by stirring at 0 °C for 30 min. The precipitated product is collected by filtration. 

Benzimidazolium triflate serves as a highly reactive promoter for the condensation of a nucleoside phosphoramidite and a nucleoside (or a nucleotide), which is a key step in the synthesis of 

In general, condensation is smoothly achieved and the subsequent oxidation provides a nucleotide in a high yield. 

IV-Phenylimidazolium triflate IV-Phenylimidazolium perchlorate 2-(Bromo)-4,5-(dicyano)imidazole IV-Methylbenzimidazolium triflate Pyridinium tetrafluoroborate IV-Methylanilinium trifluoroacetate lV-(p-Acetylphenyl)imidazolium triflate IV-Phenylimidazolium tetrafluoroborate ImidazoUum perchlorate 5-(/t-Nitrophenyl)-l//-tetrazole 4,5- (Dicy ano)imidazDle 4-(Phenyl)imidazDlium triflate Benzimidazolium tetrafluoroborate Imidazolium tetrafluoroborate Imidazolium triflate Benzimidazolium triflate 2-(Phenyl)imidazolium triflate A-Methylimidazolium triflate 4-(Methyl)imidazolium triflate l//-Tetrazole 

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It is not recommended to scale this method up to large scale because of shock sensitivity of tetrazole. An alternative catalyst is benzimidazolium triflate. See also reference 31 for more alternatives and references. 

Hayakawa Y, Kataoka M, Noyoii R. Benzimidazolium triflate as an efficient promoter for nucleotide synthesis via the phosphoramidite method. J Org Chem 61 7996-7997, 1996. 

A-Phenylimidazolium trillate A-Methylbenzimidazolium trillate Benzimidazolium triflate A-Phenylimidazolium perchlorate Imidazolium perchlorate A-Acetylphenylimidazolium triflate Pyridinium tetrafluoroborate 4,5-Dicyanoimidazole 2-Bromo-4,5-dicyanoimidazole 5-(Ethylthio)-1 //-tetrazole... 

Reaction of 68 with protected galactose (59) and benzimidazolium triflate as activator followed by oxidation or sulfurization, deprotection, and conversion into the sodium salt provided bis(phosphonate) 70 and bis(phosphonothioate) 71 (Figure 2.9) in a total yield of 5 (70) and 25% (71). 

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