Imine groups

The stabilizing activity of polyamine disulfides is specified by the imine group and the disulfide bridge, which participate simultaneously in the breaking of the chain by suppressing the radicals and in the free radical destruction of peroxides and hydroxides. 

High thermostabilizing efficiency of polyamine disulphides relative to chemically cross-linked polyethylene is conditioned by the ability to accept macroradicals at the disulphide bridge and imine group. Besides, the presence of paramagnetic centers causes the adherence of macroradicals providing for an extra stabilizing effect [49]. 

A number of the purported syntheses of dibenzo[f>,/][l,4]diazocines in the literature have to be revised and the structure of the products corrected.1 Instead of the expected 1,4-diazocine derivatives 1, isoindolobenzimidazoles 2 are actually isolated, the formation of which requires a hydride shift after transannular attack of one imine group onto the other. 

The imine group formed as a result of this reaction will then initiate the reaction of cyclization proceeding in accordance with the above scheme. 

The mercuration of ferrocenylimines with Hg(OAc)2 has been studied. - 6 Mercuration occurs selectively at the a-position relative to the imine group to afford compounds 86a-i (Scheme gy107,108 The regioselectivity of these reactions points to the directing role of the Lewis-basic imine functionality. Similar factors probably play a role in the formation of the ferrocenylketone and ferrocenylaldehyde derivatives 87a-f and 87g-j, respectively. These derivatives readily react with amines to afford the corresponding imines (Scheme 9). Presumably, the Lewis-acidic mercury center of the monomercurated ferrocenylketones and ferrocenylaldehydes activates the carbonyl functionality toward nucleophilic attack by the amine. 

Oxidative dehydrogenations of many macrocyclic ligand complexes have now been documented. Typically, these reactions involve conversion of coordinated secondary amines to imine groups. 

By using combinations of hydrogenation and dehydrogenation reactions it has been possible to obtain nickel derivatives of the Curtis macrocycle containing from zero to four imine groups (Curtis, 1968 1974). Related reactions in the presence of a variety of other central metal ions have been described. The electrochemical oxidation of the Cu(ii) complex of the reduced Curtis ligand proceeds initially via a two-electron step to yield the monoimine complex (296) (Olson Vasilevskis, 1971). 

Once again the data implicate a Cu(m) intermediate. In this case, further oxidations subsequently occur to yield a product containing four imine groups. 

The imine group in the Schiff base PhMeC=NCH2Ph has been hydrogenated to the amine with 22% ee using the cationic DIOP complex in... 

As outlined in Section II,E, ketone and imine groups are readily hydrogenated via a hydrosilylation-hydrolysis procedure. Use of chiral catalysts with prochiral substrates, for example, R,R2C=0 or R,R2C=N— leads to asymmetric hydrosilylation (284, 285 Chapter 9 in this volume) and hence optically active alcohols [cf. Eq. (41)]. 

These results also indicate that the protonation of the imine group is important for the reaction. In the o-OH and p-OH isomers, resonance between the protonated imine and quinoido species would contribute in facilitating the protonation of the imine portion (Scheme 5.17). In the m-OH isomer, however, no such resonance contribution is possible. Thus, the poor additive effect of phenol in the reaction of N-benzylideneaniline with the acylzirconocene chloride (entry 1, Table 5.3) might imply less efficient protonation of the imine, as in the case of the m-OH isomer (Scheme 5.16). 

K. Yamamoto, M. Higuchi, S. Shiki, M. Tsuruta, and H. Chiba, Stepwise radial complexation of imine groups in phenylazomethine dendrimers, Nature, 415 509-511 (2002). 

Highly reactive ions such as [FeNH]+ may transfer the ligand, in this case the imine group. The reaction of [FeNH]+ with benzene resulted in an amination reaction with the cation of aniline [PhNH2]+ produced as the major product ion (178). 

The dynamic nature of the system offers the crown ether access to the ammonium centre allowing self-assembly of the corresponding dynamic [2]ro-taxanes 31 to occur. Fixing of the interlocked assembly can be achieved by reducing the imine groups in 31 to the corresponding amine so that a kinetically inert [2]rotaxane forms. 

Tridentate ligands for cobalt and iron catalysts. The catalysts discussed earlier in the section on ethene oligomerisation can also be used for making polymers, provided that they are suitably substituted. In Figure 10.30 we have depicted such a catalyst, substituted with isopropyl groups at the aryl substituents on the imine group, as in Brookhart s catalysts [49], The initiation is now carried out by the addition of MAO to a salt of the cobalt or iron complexes. The catalysts obtained are extremely active, but they cannot be used for polar substrates. 

Must belong to a primary or secondary imine group... 

Scheme 3 Electrochemical reduction (n-doping) of n-conjugated heteroaromatic polymers. Effect of the imine group...

Reprotonation then produces a new imine (keti-mine), and also restores aromaticity in the pyridine ring. However, because of the conjugation, it allows protonation at a position that is different from where the proton was originally lost. The net result is that the imine double bond has effectively moved to a position adjacent to its original position. Hydrolysis of this new imine group generates a keto acid and pyridoxamine phosphate. The remainder of the sequence is now a reversal of this process. This now transfers the amine function from pyridoxamine phosphate to another keto acid. 

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