2,2 Bipyridyl derivatives

Building blocks, useful for supramolecular or material science, have also been prepared using the Boekelheide reaction. Thus bipyridyl derivative 23 was subjected to the standard sequence of reactions (oxidation, rearrangement, and hydrolysis) to afford the diol 24. 

JMJD2 demethylases are inhibited by analogues of the cofactor 2-OG that include N-oxalylamino acids, pyridine dicarboxylates, and related bipyridyl derivatives. Other chemotypes that are also presumed to bind to the active-site Fe(II) include catechols, hydroxamic acids (including the clinically used HD AC inhibitor SAHA/Vorinostat), and tricarboxylic acid cycle intermediates, such as succinate and fumarate [59,62]. 

Nucleophilic attack at the carbonyl-carbon of 4,5-diazafluoren-9-one (dzf, 12) coordinated to ruthenium has been demonstrated, and a mechanism outlined, for reaction of [Ru(bpy)2(dzf)]2+ with l,8-diazabicyclo[5,4,0] undec-7-ene (dbu)13, which gives a tris-2,2 -bipyridyl derivative (400). 

The rates of a number of different types of reactions of 2,2 -bipyridyl derivatives are markedly enhanced by metal chelation. The elimination reaction (6.40) in wet dmso... 

The facility for 4-metalation shown by 3-substituted pyridines is continued with bipyridyl derivatives, and thus 3,3 -bis[2-(trimethyIsilyl)ethoxy]-methyl-2,2 -bipyridine gave the 4,4 -dilithio species on treatment with n-BuLi, and this then afforded 4,4 -disubstituted bipyridines, often in very good yield (Scheme 111)(88HCA957). 

Large dendrimers based on the [PtMe2(2,2 -bipyridyl)] unit constructed around a 1,2,4,5-tetrafunctionalized benzene core and containing up to 28 platinum atoms have been reported by Puddephat, along with a related 14 platinum atom system 30 which was obtained by reaction of wedge 28 with the disubstituted 2,2 -bipyridyl derivative 29 (Scheme 5). Progression could not be continued beyond 30 because of steric congestion. 

Pyridylzinc bromide, a commercially available reagent, was used in the synthesis of a series of bipyridyl derivatives (7.20.). Activated coupling partners, such as 2-chloro-4-cyanopyridine, reacted readily at room temperature in the presence of a palladium based catalyst, while less electron deficient halopyridines were coupled at elevated temperatures.27 The same approach was also extended to the preparation of other heterobiaryls.28... 

Pentafluoropyridine (292) is reduced440 in dry DMF at a mercury cathode to perfluoro-4,4 -bipyridyl (293) in the presence of hydroquinone as proton donor, 2,3,5,6-tetrafluoropyridine (294) is obtained [Eq. (150)]. Pentachloro-pyridine gives on reduction in dry DMF very little bipyridyl derivative, but tetrachloropyridine and bis(tetrachloropyridyl) mercury. 

The organosulfinato complexes (RS02)Zn(0H2)2 react with bipy according to equation (6) (R = Ph or p-MeCeHt). In the case of the bis(bipyridyl) derivatives, both O-bonded and S-bonded linkage isomers are formed.678 The hydrated sulfinate also reacts with py to give the derivatives [(RS02)2Zn(py)] (R = Ph or p-MeCsFLt).679 The polymeric structures (99) and (100) are postulated for the two 1 1 complexes. 

The work was further extended to the replacement of CouL by Co11 bipyridyls171 (with H2A as reductant) and in this case, quantum yields of up to 0.13 were recorded. Under the conditions used ([Ru(bipy)3]2+/H2A/Co2+/bipy), the principle Co species in solution are the mono- and bis-bipyridyl derivatives and the mechanism is analogous to that proposed for ConL, involving an unstable Co111 hydride species some dihydrobipyridyl is also produced. Replacement of bipy by 4,4 -dimethyl-2,2 -bipyridyl (dmbp) increases the quantum yield, but substitution of Co2+ by Fe2+, Ni2+, Zn2+, Cu2+ or Mn2+ leads to a substantial drop in hydrogen yields. 

Figure 4.39 X-ray crystal structure of the Fe(II) complex a 2,2 -bipyridyl derived tris(imidazolium)...

In an elegant self-assembling system based on the use of cyclodextrin hosts, DeCola and coworkers noncovalently linked an alkylcarboxyan-thracene to an a-cyclodextrin bearing Ru(II) complex that also had an Os(II) bipyridyl derivative attached via noncovalent interaction with a -cyclo-dextrin substituent on the Ru complex (Fig. 14). The system yields an energy transfer cascade from the photoexcited anthracene to the Ru to bpy 3 MLCT state, which in turn transfers energy to the Os(II) complex 3MLCT state. All rate constants are > 108 s-1 [88]. 

Fumkawa, N. Shibutani, T. Fujihara, H. Preparation of bipyridyl derivatives via a-lithiation of pyridyl phenyl sulfoxides, substitution with electrophiles and cross-coupling reactions with Grignard reagents. Tetrahedron Lett. 1989, 30, 7091-7094. 

These authors have studied the effect of complexation on dynamic processes in bridged bipyridyl derivatives (138) (Scheme 101). 

The four-coordinate 2,2 -bipyridyl and triazine adducts Me2Cd(bipy),3 (Me3SiCH2)2Cd(bipy), 5 and Me2Cd[(CH2 NMe)3]2 have been isolated, and the bipyridyl derivatives (4a) have been structurally characterized by X-ray diffraction. Notably, the coordination environments about the cadmium centers in both compounds deviate substantially from tetrahedral, with large C-Cd-C bond angles (Table 3). 

Other metallocycles assembled from two ligand molecules and two metal atoms have been reported by Harding et aV Bimetallic [2+2] macrocycles from the bis(bipyridyl) derivatives 3-7 and nickel(II), copper(I), silver(I), zinc(II) and cad-mium(II) have been reported. Products of this type may have either chiral, helical... 

Russian workers have reported some terpyridyl complexes of co-balt(III) 35), and the bis(terpyridyl) cobalt(II) ion is now known. The magnetic properties of Co(terpy) depend critically on the anion present in the crystal thus, at 20°C the magnetic moments are 4.3 (perchlorate), 2.7 (bromide dihydrate), 2.1 (chloride monohydrate), and 2.2 B. M. (aqueous solution). A study of the temperature dependence of the moment for Co(terpy)2Br2 2H20 indicated that no simple explanation was possible 379). The subject has been considered more recently by Judge and Baker 412a). Some peculiar bipyridyl derivatives of cobalt(II) cyanide were reported some years ago 571) these could warrant further investigation. The UV spectra of Co(II) and Co(III) complexes have also been measured. 

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