Imidazole sidechain

Priihs et al. found an elegant application for a seemingly remote hydroxy group in the sidechain [43]. The remoteness of the hydroxy group implies a mode of introduction to the central imidazole ring different to the epoxide method developed by Arnold (hydroxyethyl) and Thiel (hydroxyhexyl). Indeed, Priihs et al. modilied the classic method of imidazo-lium salt synthesis by using a bromoalkane as carrier for the hydroxy functional group. In this way, they reacted A-mesityl imidazole with l-bromo-ta-hydroxyalkanes to obtain the... 

Amino acids are the monomers from which nature produces proteins and enzymes. As such, they form an important part of the chiral pool. Histidine contains an imidazole ring in the sidechain and thus is a logical target for the synthesis of functionalised and chiral NHC, Given that a primary amine, as found in natural amino acids, is a prerequisite for standard imidazole ring forming reactions [60], it is surprising that only a few protocols are found in the literature where an amino acid [61-66] or its respective alcohol [64,67] forms part of a reaction that leads to a carbene precursor,... 

As mentioned before, the distance between the imidazole ring and the amino function in histamine and the Hg agonist immepip is quite different (Fig. 1). Following this observation we recently synthetized a new series of histamine homologues which only differed in the length of the alkylamineo sidechain [38]. 

In a very detailed X-band cw-ENDOR study, LoBrutto et al. revealed an essential difference between the NO-ligated heme in cytochrome c oxidase and those of NO-ligated myoglobin and model NO-heme-imidazole complexes [70]. They discovered in the former protein a unique proton stemming from a nearby protein sidechain that perturbs the axial ligand. 

After its discovery in 2002, the copper-catalysed azide-allg ne dipolar cycloaddition (CuAAC) click reaction has found widespread application in glycoscience due to its broad tolerance of functional groups, offering high specificity and yield. It has found application in glycoproteins synthesis as well, for instance, in the transformation of the amine sidechain of lysine into an azide by treatment with imidazole-1-sulfonyl azide for subsequent CuAAC modification. Such methodology... 

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