Electron-transfer processes, nitrogen

These are involved in a wide range of electron-transfer processes and in certain oxidation-reduction enzymes, whose function is central to such important processes as the nitrogen cycle, photosynthesis, electron transfer in mitochondria and carbon dioxide fixation. The iron-sulfur proteins display a wide range of redox potentials, from +350 mV in photosynthetic bacteria to —600 mV in chloroplasts. 

The copper proteins with a type 1 active site are commonly known as blue copper proteins due to their intense blue color in the Cu11 state. They are usually participants in electron transfer processes, and the best-known representatives of this class include plastocyanin, azurin and amicyanin [1]. The copper center in the type 1 active site is surrounded by two nitrogen donor atoms from two... 

The formation of five-membered y-lactam 64 in high yield was also reported [22] subsequently by the photolysis of N,N-dibenzyl-2-benzoylacetamide (63) in benzene. The presence of acyl moiety in 63 suppressed the basicity of the nitrogen lone pair and prevented its involvement in the quenching of the carbonyl excited state by an electron-transfer processes (Scheme 8.19). 

Aryl radical cations generated by electron-transfer processes from methoxy substituted arenes to DCN, tethered by oxygen, nitrogen as well as carbon nucleophile leads to intramolecular cyclizations (Scheme 8.67). The synthetic potentials of... 

The use of <7-2,4-dinitrophenyl oximes has lead to a novel method for the generation of alkylideneaminyl radicals by a one-electron transfer process from phenol derivatives. These species thus generated are smoothly captured with an internal aryl or olefin moieties. This represents a new, very useful tool for the preparation of nitrogen-containing heterocycles. 

The photochemical reactions of ethyl phenylglyoxalate (217) in benzene have been re-examined. The three new products (218), (219) and (220) have been isolated from the reaction mixture. The quantum yields for the formation of the products are dependent on concentration. Irradiation of the phenylglyoxalate derivatives (221) results in conversion into the lactones (222) from (221, R = H) and (223) and (224) from (221, R = Me). The reactions are proposed to involve an intramolecular electron transfer process forming a zwitterionic biradical. This leads to activation of the methylenes adjacent to the sulfur atom. A similar effect is observed with the nitrogen analogue (225) which affords (226) as the... 

Topics that have formed the subjects of reviews this year include contemporary issues in electron transport research, dynamics of bimolecular photoelectron transfer reactions, photophysical properties of functionalised fullerene derivatives, carbon-carbon bond formation via radical ions, photoinduced electron transfer processes in ketone, aldehyde, and ester synthesis, photochemical reactions between arenenitriles and benzylic donors, photo-oxidation of conjugated dienes, photoredox reactions of aromatic nitro compounds, electron transfer-mediated photochemistry of some unsaturated nitrogen-containing compounds, reactions of 02( Ag), carbon dioxide activation by aza-macrocyclic complexes, and photochromism of chalcone derivatives. ... 

N,N-Disubstituted O-Alkylhydroxylamines. In the amination with a series of N,N-disubstituted O-methylhydroxylamines, more bulky alkyllithium compounds react more readily (product 4, Eq. 10).85 The small amounts of products 5 are the result of elimination of methanol from the substrate to give the imine followed by addition of RxLi to the latter. Reagents where R2, R2 is H, Me or Me, Me do not react. A single-electron-transfer process involving a nitrogen radical has... 

Protein-mediated electron transfer is a device used in a diverse array of biological transformadons. Well-known electron transfer processes include the mitochondrial electron transport system, photosynthesis (Chapter 13), and nitrogen flxadon (Chapter 15). Less well known biochemical reactions in which electron transfer plays a crucial role include nitric oxide synthesis and the cytochrome P450 electron transport systems. Each of these mechanisms is briefly oudined. 

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