Oxidative generation pools

The cation pool method is based on the irreversible oxidative generation of organic cations. In the first step, the cation precursor is oxidized via an electrochemical method. An organic cation thus generated is accumulated in the solution in the absence of a nucleophile that we want to introduce onto the cationic carbon. Counter anions which are normally considered to be very weak nucleophiles are used to avoid the nucleophilic attack on the cationic center. In order to avoid thermal decomposition of the cation, electrolysis should be carried out at low temperatures such as -78 °C. After electrolysis is complete, the nucleophile is then added to obtain the desired product. The use of a carbon nucleophile results the direct carbon-carbon bond formation. 

Methods for the Oxidative Generation of Cations for Use in Cation Pools ... 

Four methods are used for generating pools of these onium ions oxidative C-H bond dissociation, oxidative C-Si bond dissociation, oxidative C-S bond dissociation, and oxidative C-C bond dissociation (Scheme 3). In the following sections, we will discuss the principles and synthetic applications of these methods. 

Okajima M, Soga K, Nokami T et al (2006) Oxidative generation of diarylcarbenium ion pools. Org Lett 8 5005-5007... 

In some cases, particularly with iaactive metals, electrolytic cells are the primary method of manufacture of the fluoroborate solution. The manufacture of Sn, Pb, Cu, and Ni fluoroborates by electrolytic dissolution (87,88) is patented. A typical cell for continous production consists of a polyethylene-lined tank with tin anodes at the bottom and a mercury pool (ia a porous basket) cathode near the top (88). Pluoroboric acid is added to the cell and electrolysis is begun. As tin fluoroborate is generated, differences ia specific gravity cause the product to layer at the bottom of the cell. When the desired concentration is reached ia this layer, the heavy solution is drawn from the bottom and fresh HBP is added to the top of the cell continuously. The direct reaction of tin with HBP is slow but can be accelerated by passiag air or oxygen through the solution (89). The stannic fluoroborate is reduced by reaction with mossy tin under an iaert atmosphere. In earlier procedures, HBP reacted with hydrated stannous oxide. 

ElectrolyticaHy generated hypochlorite may be used for the oxidative destmction of cyanides (qv) or the sterilization of domestic wastes. Several on-site systems for swimming pool sterilization and municipal waste treatment works have been developed. One of these systems is described in Reference 124. On-site production and immediate use of chlorine is considered safer than the transportation of chlorine. 

Sakaida, S., Kyle, M. and Farber, J.L. (1990). Autophagic degradation of protein generates a pool of ferric iron required for the killing of cultured hepatocytes by an oxidative stress. Mol. Pharmacol. 37, 435-442. 

Rotenone inhibits the transfer of electrons from NADH into the electron transport chain. The oxidation of substrates that generate NADH is, therefore, blocked. However, substrates that are oxidized to generate FADH2 (such as succinate or a-glycerol phosphate) can still be oxidized and still generate ATP. Because NADH oxidation is blocked, the NADH pool becomes more reduced in the presence of rotenone since there s nowhere to transfer the electrons. 

In the cation pool method organic cations are generated by electrochemical oxidation and are accumulated in a solution. In the next step, a suitable nucleophile is added to the thus-generated solution of the cation. In the cation flow method organic cations are generated by electrochemical oxidation using a microflow cell. The cation thus generated is allowed to react with a nucleophile in the flow system. 

Generation of Alkoxycarbenium Ion Pools by Oxidative C-S Bond Cleavage... 

Alkoxycarbenium ion pools can also be generated by oxidative C-C bond dissociation. Oxidative C-C bond dissociation is well known in the literature.38 Thus, the electrochemical oxidation of l,2-dimethoxy-l,2-diphenylethane 32... 

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