Copper xylyl

From this perspective they reported the structure (complex (791) Cu-Cu 10.061 A) of a m-xylyl-based TACN ligand.583 Structures of four mononuclear copper(I) complexes ((792)-(795)), supported by tridentate macrocycle, were also reported by this group. They investigated their oxygenation behavior and in each case clean formation of side-on peroxo-dicopper(II) species was demonstrated.416... 

At present, we do not completely understand why only some of these very similar m-xylyl dicopper(I) complexes systems described above undergo ligand oxygenation reactions. However, based on the results outlined above, we can speculate on a number of aspects of this 02-activation process. Our studies implicate the presence of a copper-dioxygen (peroxo dicopper(II)) adduct as an intermediate in the oxygenation reaction and more recent kinetic studies (51) further support this conclusion. This adduct then either directly or via some further intermediate undergoes an electrophilic attack of the arene. The unique nature of this very fast reaction 2->3, and the observed inability to intercept the active... 

Mefenamic acid Mefenamic acid, A -(2,3-xylyl)anthranylic acid (3.2.19), is synthesized in basically the same manner, by the reaction of the potassium salt of 2-bromobenzoic acid with 2,3-dimethylaniline in the presence of copper (11) acetate [80,81]. 

III.B.1. A Xylyl-Containing Copper Monooxygenase Model System... 

Concerning the mechanism, the suggestion of cationic intermediates and an oxidatively induced methyl migration reaction lead to a suggested mechanism for this unique example of a N.I.H. shift in copper chemistry, one that is also consistent with all the other chemical observations and kinetic studies carried out on these xylyl copper complexes (Figure 14). 

Figure 14 Unified mechanism of xylyl hydroxylation reactions, accounting for Cu202 intermediate [11] formation and copper-mediated N.I.H. shift (1,2-migration) reactions.

Drury III, L. Ryzhkov, A. E. Taggi, T. Lectka, J. Am. Chem. Soc. 2002, 124, 67 for an example using chiral copper complexes derived either from xylyl-BINAP or chiral diamines, see i) S. Kobayashi,... 

Figure 6. Scheme showing the nature of products (i.e., 9, PY2, formaldehyde and Me-PY2) obtained during the oxygenation of methyl-substituted xylyl ligand complexes [Cu2(R-XYL-Me)]2+ (6, X = Me). The proposed mechanism of copper mediated arene hydroxylation and NIH shift (1,2-migration) reactions is also outlined. 

These and other observations (51-55) suggest that the tendency towards hydroxylation in these kinds of chemical systems is very sensitive to electronic effects, as well as copper chelation and peroxide proximity and orientation toward xylyl substrate. This view is supported by observations involving an unsymmetrical system, [Cu2(UN)]2+ (56), an analogue of [Cu2(XYL)]2+ (6)... 

Thus, the two tetramine receptors cyclam and tren were linked by a 1, 4-xylyl spacer to give system 14, tren-cyclam. The heterodimetallic complex [Cu(II)(tren)-Ni(II)(cyclam]4+ operates chloride anion translocation between copper and nickel centers, through the Ni(II)/Ni(III) couple, in an MeCN solution [36]. In particular, when 1 equivalent of CP is added to an MeCN solution of the heterodimetallic complex [with the nickel center in the Ni(II) state], the anion goes on the Cu(II) ion. In particular, since the log K value for the 1 1 adduct formation equilibrium is 5.7, in a lO-3 M solution of the heterodimetallic complex, 95% of the CP ion is bound to Cu(II), while the remaining 5% is dispersed in the solution. The solution has a blue-green color, due to an absorption band centered at 460 nm, pertinent to the [Cu(II)(tren]2+ fragment of the heterodimetallic complex [Cl-to-Cu(II) CT transition). If in an... 

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