2,2 :6 ,2"-Terpyridines, synthesis

Landsmann, S. Winter, A. Cbiper, M. Fuston, C.-A. Hoeppener, S. Wouters, D. Gohy, J.-F. Scbubert, U. S., Poly(dimeth siloxane)-Substituted 2,2 6,2 -Terpyridines Synthesis and Characterization of New Amphiphihc Supramolecvdar Dihlock Copolymers. Macromol. Chem. Phys. 2008,209, 1666-1672. 

Newkome employed this methodology in his synthesis of halogenated terpyridines. The requisite pyridinium ion 62 was prepared from the corresponding... 

Recently, Newkome et al. [165] described the synthesis of dendritic lock and key complexes, such as 78, which is based on the well-researched bzsterpyridine-ruthenium (—(Ru)—) coordination chemistry (Fig. 33). Dendritic terpyridines of the first and second generation were reacted with RuC13 and this formed the... 

For instance, some time ago Newkome et al. reported the synthesis of ruthenium based dendrimers [170]. A dendrimer (80) with twelve peripheral terpyridine ligands was built around a central quaternary carbon-based core. In the final step complexation between the terminal ligand of the dendrimer and a terpyridinyl ruthenium chloride building block afforded the dodecaruthenium cascade molecule 80 (Fig. 35). Thus, preconstructed cores and dendritic fragments were linked by Ru2+ as the connecting unit and this mode of connectivity could be denoted by [—(Ru)—]. 

Astruc et al. [187] reported a nonairon sandwich complex by treating a nona-ol with [C5H5]Fe(q6-p-MeC6H4F)(PF6). In a subsequent report [188], Astruc and Marvaud reported the synthesis of aromatic star molecules with or without a central Fe(/f-C5H5)+ group. These bipyridine and terpyridine terminated dendrimers were further capped with [Ru(bipy)2Cl2] and [Ru(terpy)Cl3], respectively, to afford the corresponding hexa or hepta nuclear complexes. 

A general strategy developed for the synthesis of supramolecular block copolymers involves the preparation of macromolecular chains end-capped with a 2,2 6/,2//-terpyridine ligand which can be selectively complexed with RUCI3. Under these conditions only the mono-complex between the ter-pyridine group and Ru(III) is formed. Subsequent reaction with another 2,2 6/,2"-terpyridine terminated polymer under reductive conditions for the transformation of Ru(III) to Ru(II) leads to the formation of supramolecular block copolymers. Using this methodology the copolymer with PEO and PS blocks was prepared (Scheme 42) [ 107]. 

Pyridine-pyridine connections via a Stille reaction have been well precedented for the syntheses of bipyridine, terpyridine, tetrapyridine and other oligomers of pyridine [73-75]. These reactions are exemplified by the synthesis of tetrapyridine 84 [75] from terpyridyl chloride 83 and 2-tributylstannylpyridine. 

In a very recent set of papers [48,54,59,60,131,132,324-328], the synthesis and characterization of metallosupramolecular amphiphilic block copolymers containing a hydrophilic PEO block linked to a hydrophobic PS or PEB block through a fozs-2,2/ 6/,2/terpyridine-ruthenium(II) complex have been described. These copolymers form the so-called metallosupramolecular micelles . 

A relatively unexplored method to prepare a pyridine ring by thermolysis of O-allyl cyclic oximes (593) was used in the synthesis of some unsymmetrical bridged terpyridines and in the synthesis of the E-ring in modified steroids" (equation 261). 

Phenylmethylsilanediol, synthesis, 42 155 Phenylsilanetriol, monosodium salts, 42 169 4 -Phenyl-2,2 6, 2 -terpyridine bis nickel complex, 30 74 molecular structure, 30 74 PhjtfluorenyllSiOH, 42 197 (Ph(Me2N)C-=Nli], 37 59-65 orientation of imino ligand, 37 61-63 (PhMe SiljCSiH OH, 42 244-245, 248 (PhMe SiljCsiMeHlOH), 42 191 Phosphaalkenes acyclic, 33 338-353 butadienes, 33 346-349 cumulenes, 33 352... 

Lohmeijer BGG, Schubert US. Water-soluble building blocks for terpyridine-containing supra-molecular polymers synthesis, complexation, and pH stability studies of poly(ethylene oxide) moieties. Macromol Chem Phys 2003 204 1072-1078. 

A number of routes are available for the synthesis of 2,2 -bipyridines where one of the pyridine rings is built up from simpler entities. For example, condensation of 2-(aminomethyl)pyridine (31) with acetaldehyde or acetylene over a silicon-alumina catalyst at 450°C gives 2,2 -bipyridine, ° whereas 2-cyanopyridine reacts with acetylene at 120°C in the presence of a cobalt catalyst to afford 2,2 -bipyridine in 95% yield.2-Acetylpyridine with acrolein and ammonia gives 2,2 -bipyridine in the presence of dehydrating and dehydrogenating catalysts, and related condensations afford substituted 2,2 -bipyridines. ° In a similar vein, condensation of benzaldehyde with 2 mol of 2-acetylpyridine in the presence of ammonia at 250°C affords 2,6-di(2-pyridyl)-4-phenylpyridine, ° and related syntheses of substituted 2,2 6, 2"-terpyridines have been described. Likewise, formaldehyde with two moles of ethyl picolinoylacetate and ammonia, followed by oxidation of the product and hydrolysis and decarboxylation, affords a good... 

The most important synthesis of 4,4 -bipyridine involves the reaction of sodium on pyridine. This reaction was discovered as long ago as 1870, although the product was not deduced to be 4,4 -bipyridine until later. " 4,4 -Bipyridine is the predominant isomer formed, although varying amounts of other isomeric bipyridines, especially 2,2 -bipyridine and 2,4 -bipyridine, may be formed, depending on the reaction conditions. The reaction involves formation of the sodium derivative of pyridine, which is formulated as the radical 67. It then couples predominantly in the 4 positions to afford 68, which with water hydrolyzes to l,T,4,4 -tetrahydro-4,4 -bipyridine. Facile oxidation then gives 4,4 -bipyridine. ° If the reaction is carried out at the temperature of boiling pyridine (IIS C) instead of at lower temperatures, the proportion of bipyridines other than 4,4 -bipyridine increases, and some terpyridines may be formed as vvell. Oxidants... 

The procedure described here is by far the most efficient synthesis of terpyridine. Previous preparations include the dehydrogenation of pyridine with ferric chloride, the Ullman reaction of 2-bromopyrid1ne and 2,6-dibromopyridine,5 the action of copper on 2-bromopyridine and 6-bromo-2,2 -... 

The present approach to terpyridine is a two-step procedure based on a variation of the Potts strategy.11 In this sequence, the 1,5-enedione formation is accompanied by the loss of dimethyl amine and the ring closure gives terpyridine directly, thus avoiding both drawbacks of the Potts method. The synthesis of the intermediate enaminone (1) has been previously reported.12... 

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