With Pyridyl Derivatives

Mel, CH3CN morpholine or diethylamine, methanol, 76-95% yield. These conditions also cleave tlie 4 -pyridyl derivative. The Pet ester is stable to the acidic conditions required to remove the BOC and r-butyl ester groups, to the basic conditions required to remove the Fmoc and Fm groups, and to hydrogenolysis. It is not recommended for use in peptides that contain methionine or histidine since these are susceptible to alkylation with methyl iodide. 

Reaction of 10-bromo-iV,l,3-trimethyl-7-oxo-2,3-dihydro-7//-pyrido [ 1,2,3-i/e]quinoxaline-6-carboxamide with 2,6-dimethyl-4-(tributylstannyl)-pyridine in the presence of (Ph3P)2Pd(II)Cl in boiling toluene gave 10-(2,6-dimethyl-4-pyridyl) derivative (OOMIPIO). 

Recently, it has been reported that methyl 2-pyridyl sulphoxides (10) and related pyridyl derivatives (11) (see Schepie 25) are good phase transfer catalysts for SN2 reactions of various primary or secondary alkyl halides in a two-phase reaction system and for the alkylation of phenylacetonitrile or phenylacetone with alkyl halides in liquid-liquid two-... 

If the free-base porphyrin is tetrasubstituted at the meso positions with 3- or 4-pyridyl ligands, pentamers are obtained on coordination to zinc porphyrin dimers (79) (65,66, Fig. 24). With the 3-pyridyl derivative all the porphyrin planes are coplanar, whereas in the case of the 4-pyridyl derivative the ligand porphyrins are approximately perpendicular to the plane of the zinc porphyrins. Quenching of the zinc porphyrin... 

Blue luminescence of zinc complexes of pyridyl-containing complexes is an area of current interest.277 Design of blue luminescent materials is of relevance to display applications, as blue-light-emitting diodes, and to this end Che examined solution luminescence of zinc pyridylamine complexes.73,278 Che and co-workers studied the complex Zn40(7-azaindoyl)6 which has a blue emission at 433 nm in the solid state.279,280 In an attempt to improve on stability Wang et al. examined compounds with neutral 7-azaindole and an A-functionalized pyridyl derivative.281 In contrast with other metal complexes of the neutral 7-azaindole (32), Zn(7-azaindole)2(OAc)2 is a blue luminescent compound and a A-(2-pyridyl) 2-azaindole (33) and its complexes were also... 

Recently, Malpass et al. reported a synthesis of epibatidine isomers also under reductive Heck conditions [134, 135]. 2-Azabicyclo[2.2.1]heptene 167 was assembled by cycloaddition of an iminium salt with cyclopentadiene. Treatment of 167 with 2-chloro-5-iodopyridine provided a mixture of exo-5-(6-chloro-3-pyridyl) derivative 168 and exo-6-(6-chloro-3-pyridyl) derivative 169. 

The proposed mechanism is consistent with the experimental results obtained so far. For instance the effects of cation size and -coordination are readily understood in terms of the chelated complex [10a] as is the absence of stereoselectivity in the case of the corresponding 4-pyridyl derivatives where coordination with cation in the manner shown above is impossible. The similarity between vinyl addition and methylation stereochemistry is likewise consistent with the proposed mechanism. Thus it is the equilibrium between [10] and [11] that is primarily responsible for the observed stereochemistry. Work on the stereochemistry of other electrophylic reactions of [2a] is in progress. 

The electrochemical properties of another series of Cu(I) complexes, based on substituted bipyridine and quinoline derivatives, have been also investigated68 (Fig. 17.31). To stabilize the Cu(I) oxidation state of Cu(I) polypyridine complexes, electron-withdrawing substitutents like esters have been considered. The same effect was also obtained with pyridyl-quinoline and biquinoline complexes, thanks to the increased 7i-accepting properties of the quinoline condensed aromatic ring. 

In comparison with the structurally similar 2-pyridyl derivatives this series of ligands can be more easily prepared and offer chelating positions with a more open bite angle, a feature that could influence both the stability of the derivatives formed and their structural framework. 

Formation constants for 1 1 and 2 1 Ag1 complexes with ethylenediamine Schiff bases of the type RCH=NCH2CH2N=CHR, have been reported (Table 53).392 Based on the higher stability of the pyridyl derivative, it was claimed that the pyridyl N participated in the coordination. 

Fig. 15.17. Current in milliamperes cm-2 for CO production from C02 using C02+ tetraphenyl porphyrins modified with various pyridyl derivatives. (Reprinted with permission from T. Atoguchi, A. Aramata, and M. Engo, C02 Reduction by Macrocyclic Transition Metal Complex-Modified Electrodes," in Proc. International Symposium on Chemical Fixation of Carbon Dioxide, p. 338, Fig. 5,1991.)...

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