Tetraalkylammonium cleavage

Here, the relative stability of the anion radical confers to the cleavage process a special character. Thus, at a mercury cathode and in organic solvents in the presence of tetraalkylammonium salts, the mechanism is expected16 to be an ECE one in protic media or in the presence of an efficient proton donor, but of EEC type in aprotic solvents. In such a case, simple electron-transfer reactions 9 and 10 have to be associated chemical reactions and other electron transfers (at the level of the first step). Those reactions are shown below in detail ... 

Oxidation with permanganate588 592 636 637 usually requires the use of a suitable solvent mixture, such as aqueous THF,638 which dissolves both permanganate and the alkene. Better results may be obtained by phase-transfer agents.440 Reaction with tetraalkylammonium permanganate may allow selective cleavage of a phenyl-substituted double bond in dienes.639... 

The most common and simplest cleavage of double bonds to carboxyls is achieved with potassium permanganate [555, 841, 843, 852, 860, 869, 874] or sodium permanganate 834] in aqueous solution (equation 113) or with tetraalkylammonium permanganate in organic solvents (equation 114) [845, 872, 899]. 

Because the use of aprotic media allows one to reach more reducing potentials and thus widens greatly the potentialities of the method, most recent studies on the deprotection of amines are conducted in DMF or acetonitrile, with added tetraalkylammonium electrolytes and proton donors. Often mercury cathodes are used, when strong adsorption phenomena are mentioned35. The reductive deprotection of threonine (cleavage of its N-arenesulphonyl amide) was investigated36 both chemically and electrochemically ... 

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