Imidazole 27-----------------Imines

Starting from the benzylidene diimine 24 (Scheme 15) and only one equivalent of TosMlC, the same reaction afforded the imidazole-imine derivative and then, after alkylation, the corresponding salt 25. After hydrolysis, an... 

Scheme 21 Imidazole-imine C-C coupling and protonation of the resulting amido group to afford cationic amino complexes.

N-silylated imines 509 react with the Li salts of tosylmethylisonitriles to give 4,5-disubstituted imidazoles in moderate yields [93]. Acetylation of N-trimethylsilyl imines 509 with acetyl chloride and triethylamine affords 72-80% of the aza-dienes 510 these undergo readily Diels-Alder reactions, e.g. with maleic anhydride at 24 °C to give 511 [94] or with dimethyl acetylenedicarboxylate to give dimethyl pyridine-3,4-dicarboxylates [94] (Scheme 5.29). 

Biosorption is a rather complex process affected by several factors that include different binding mechanisms (Figure 10.4). Most of the functional groups responsible for metal binding are found in cell walls and include carboxyl, hydroxyl, sulfate, sulfhydryl, phosphate, amino, amide, imine, and imidazol moieties.4 90 The cell wall of plant biomass has proteins, lipids, carbohydrate polymers (cellulose, xylane, mannan, etc.), and inorganic ions of Ca(II), Mg(II), and so on. The carboxylic and phosphate groups in the cell wall are the main acidic functional groups that affect directly the adsorption capacity of the biomass.101... 

Unsymmetric compartmental ligands that allow for the controlled synthesis of unsymmetric Ni2 or heterobimetallic NiM complexes have received particular attention.1876,1892 A wide range of such ligands derived particularly from 2-hydroxy-3-hydroxymethyl-5-methylbenzaldehyde and 2-hydroxy-3-hydroxymethyl-bromo-benzaldehyde has now been prepared and used for Ni com-plexation. These ligands have monopodal iminic pendent arms and either mono- or dipodal aminic pendent arms and the terminal donors of the pendent arms can be provided by pyridine, imidazole, and tertiary amino groups.1893-1897 Complexes are usually prepared by reaction of the requisite Ni11 salts with the preformed ligand. 

Formal insertion reactions into the N—H bond of imidazoles (Sect. 4.2) and imines (Sect. 5.1) have already been discussed. 

The Suzuki coupling of soluble polyethylene glycol (PEG)-bound bromothiophene 71 and p-formylphenylboronic acid provided biaryl 72 [56]. Due to the high solubilizing power of PEG, the reaction was conducted as a liquid-phase synthesis. Treatment of 72 with o-pyridinediaminc resulted in a two-step-one-pot heterocyclization through an imine intermediate. Nitrobenzene served as an oxidant in the ring closure step. Finally, transesterification with NaOMe in MeOH resulted in l//-imidazole[4,5-e]pyridine 73. 

---