3,3 -Bipyridine derivatives

Several substituted pyridines have been examined using the degassed Raney nickel, and the results are summarized in Table I. As all the biaryls obtained formed colored chelates with either ferrous or cuprous ions, they must be derivatives of 2,2 -bipyridine. Structural ambiguities cannot arise with 2,2 -bipyridines derived from 2- and 4-substituted pyridines but 3-substituted pyridines could conceivably give three isomeric 2,2 -bipyridines (e.g., 3, 4, 5). In fact, however, each 3-substituted pyridine so far examined has given only one 2,2 -bipyridine. 

Reaction of -picoline over degassed Raney nickel was found to give 5,5 -dimethyl-2,2 -bipyridine (5), the structure of which was established by its synthesis from 2-bromo-5-methylpyridine. Oxidation of this dimethyl-2,2 -bipyridine, and similar oxidation of the diethyl-2,2 -bipyridine derived from 3-ethylpyridinc, gave the corresponding dicarboxylic acid and the same acid was produced by the action of degassed Raney nickel on sodium nicotinate (in water) or on ethyl nicotinate. These transformations established the 5,5 -substitution pattern for three 2,2 -bipyridines derived from 3-substituted pyridines but such evidence is not available for the biaryls... 

Bipyridine-derived cycloaurated complexes have also been synthesised through the transmetallation route. Conversion of 6-phenyl-2,2 -bipyridine to its organomercury derivative 58, followed by reaction with Na[AuCl4] gave the cycloaurated complex 59 in 38% yield as its [AuC14] salt.39... 

SEM ethers.1 The synthesis of orelline (4), a 2,2-bipyridine derivative, from the SEM ether (1) of 2-bromo-3-hydroxypyridine involves metal-halogen exchange... 

The N,P phosphine-oxazoline chelate (59) is chiral, and complexes can act as homogeneous catalysts for asymmetric synthesis the Ir(l) and Pd(II) complexes promote enantioselective olefin hydrogenation and allylic substitution respectively. An N,P analog of the N,N didentate ligand 2,2 -bipyridine is (60), the soft P donor helping to stabilize low-valent metals. Further, 2,2-bipyridine derivatives such as (61) can bind metals such as Ir and Ru as N,C chelates with one pyridine nitrogen rotated to the opposite side, away from the metal ion. 

The formation of three-stranded, helical (synthetic) proteins has been shown to be influenced by metal-ion binding to ligands that form part of the component peptide strands. In one study of this type, a 15-residue amphiphilic peptide containing a 2,2 -bipyridine derivative situated at the N-terminus was demonstrated to self-assemble spontaneously in the presence of selected transition metal ions to form a 45-residue metalloprotein with a triple-helical, coiled-coil structure. 

Table 3.7 Preparation of symmetrically di- or tetra-substituted 2,2 -bipyridine derivatives 76.87,88...

Reaction of the lithium salts of various substituted pyridines with phosphorus oxychloride afforded cleanly the 2,2 -bipyridine derivatives. In the case of 2,6-dibromopyridine, the reaction led to a good yield of 6,6 -bipyridine (70%).25... 

To examine the relationship between the low-energy luminescence and intramolecular metal-metal distances, a series of [Pt2(CANAN)2(/U-L)]n+ (HCANAN=4-(aryl)-6-phenyl-2,2 -bipyridine) derivatives supported by different bridging ligands (L) have been prepared by Che and coworkers [17]. Subsequent spectroscopic assignments of cyclometalated platinum(II) or palladium(II) derivatives were made by comparing their emission energies with those of the [Pt2(CANAN)2(//-L)]n+ complexes. 

Cyclocondensation between l,2-dihydroquinoxalin-2-ones and l,2,4-triazine-3,5-dione derivatives involves the carbonyl group of the 1,2,4-triazinedione and not the carbonyl group of the quinoxalinones <04JHC597>. New examples of the synthesis of pyridine and 2,2 -bipyridine derivatives from a variety of substituted 1,2,4-triazines through Diels-Alder reactions have been described <04T8893>. 

Currently, 2,2 -bipyridine derivatives figure prominently in supramoiecular assembly,9 in bioinorganic contexts,10 in studies of redox electrocatalysis43 and in polymeric materials.11 Haiomethyl bpys and their various metal complexes have also been used as initiators for controlled polymerizations of several different monomers including styrene and 2-alkyl-2-oxazolines.12... 

The same type of columnar structure is also proposed for other polycatenar materials, such as tetrone derivatives [51], phasmidic macrocyclic liquid crystals [52], silver (I) complexes [53], or 2,2 -bipyridine derivatives [54]. 

Selective Electrocatalytic Reduction of CO2 on Electroprepared [Ru(L)(CO)2] Polymeric Film L = 2,2 -Bipyridine Derivatives... 

In view to reach this goal we have developed over the last few years (5) an electrocatalytic stem based on a new kind of organometallic polymeric films, such as [Ru(L)(CO)2]h (L = 2,2 -bipyridine derivatives), containing metal-metal bonds (Fig. 1(a)). These molecular cathodes appear to be highly selective for reduction of CO2 into CO or HCOO at a radier low overvoltage in pure aqueous electrolyte 6-8),... 

V. K.-M. Au, W. H. Lam, W.-T. Wong and V. W.-W. Yam, Luminescent Cyclometalated Allqmylgold(III) Complexes with 6-Phenyl-2,2 -Bipyridine Derivatives Synthesis, Characterization, Electrochemistry, Photophysics, and Computational Studi, Inorg. Chem., 2012, 51, 7537-7545. 

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