Introduction single-electron oxidation

Radical cations, generated by single electron oxidation of enamines that are generated in situ by the reaction of aldehydes with a chiral imidazolidinone, serve as a new class of electrophiles for silyl enol ethers (Scheme 3-1and allylsilanes. This novel Umpolung strategy allows the introduction of a chiral center at the a-position of aldehydes with these silicon reagents. The chiral imidazolidinone works as an... 

B) Cyclic electron flow, illustrated in Fig. 3 (B), is facilitated by the introduction of both the oxidized and reduced forms of a single electron carrier, in this case, TMPD. While the reduced form of TMPD can donate electrons to P700, the oxidized form of TMPD (Wurster s Blue, abbreviated as TMPDT can serve as an artificial electron acceptor in photosystem I. Since TMPD has an absorbance band in the region of 575 nm, observation of its absorbance changes is quite convenient in this system. 

As was mentioned in the introduction and is discussed more fully under catalysis by iron salts, it is possible for hydrogen peroxide to react by single electron transfers thus giving rise to the free radicals HO- and HO2. Mechanisms for the reactions of the halides and halogens based on these ideas have been proposed by Weiss (26) and by Abel (27). The oxidation of iodide may be formulated ... 

Numbers in parentheses show the oxidation lever of the iron of peroxidase compounds. Peroxidase cycle is composed of Reactions ai, a>, and Oj. No direct evidence has been obtained which indicates that III is reduced to I itself by the introduction of a single electron... 

Structure-Reactivity Relationship of Olefins. The relative reactivity of a series of olefins toward the potent oxidizing species, X, formed by the interaction of TPP Mn(II) with 02, was investigated by means of a competitive reaction technique. As shown in Table VII, the relative reactivity of an olefin, as followed by gas-liquid chromatographic determination, increases on introduction of an alkyl substituent onto the olefinic carbon atom other than the reacting carbon atom. However, the introduction of an alkyl substituent onto the reacting carbon atom reduces (or compensates) the accelerative electronic effect, as seen in the comparison between cyclohexene and n-hexene. This situation becomes clearer if one compares the two dialkyl ethylenes, cyclohexene and methylenecyclohexane, where the former has a single substituent on the reacting carbon and the other has none the observed relative reactivity is 1 27.2. 

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