4.7- Dimethoxy-l,10-phenanthroline

A stoichiometric quantity of 1,10-phenanthroline (L13) was the first ligand used for copper-catalyzed arylation of imidazole with aryl iodides (Table 9.4, entry 1) [18]. As an ejctension of this methodology, Cu2O/4,7-dimethoxy-l,10-phenanthroline (LI4) was found to be more effective, the coupling reaction occur-ing at 80-110 °C in the presence of CS2CO3 and using n-PrCN as a solvent (entry 2 ) [19, 20]. 

The group of Buchwald has developed a copper/4,7-dimethoxy-l,10-phenanthroline system enabling the N-arylation of a various imidazole derivatives (Table 1, entry 5 L9, R = OMe) [51, 52]. Note that no general useful palladium catalytic systems have been described for this type of coupling. The use of a solid-liquid phase transfer catalyst, the polyethylene glycol (PEG), and a 2,000 times turnover achieved from iodobenzene and imidazole are interesting features of this procedure. 

Continuous irradiation at 400 nm of a solution of [Ru(bipy)3p and PhCHjS in dry oxygen-free MeCN has been observed to give a quantitative yield of [Ru(bipy)3]. In the presence of BU4NQO4, this same system can act as a two-compartment cell if coupled with the reduction of a weak electron-acceptor such as 9,10-anthraquinone, 1,3-dinitrobenzene, or 2,6-dimethoxy-p-benzoquinone. The temperature dependence of the reductive quenching of electronically excited [RuLj] (where L = bipy or 4,7-dimethyl-l,10-phenanthroline) by aromatic amines in MeOH has been studied and fitted by theoretical expressions. Activation parameters for a series of quenching reac-... 

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