Indoles acetoxylation

Electrochemical oxidation of indole [202] and N-methylindole [203] in acetonitrile gives rise to dimers and trimers. These are oxidised further to polymers. Oxidation of N-acetylindoles in acetic acid results in acetoxylation of the heterocyclic... 

The acylation of arenes with alcohols has been shown to be possible using a palladium chloride catalyst in the presence of f-butylhydroperoxide. In 2-arylpyridines, substitution is directed to the ortho-position and, after initial paUadation, the formation of intermediate (59) is likely before reductive elimination yields the acylated product. The regioselective acetoxylation of indoles, at the 3-position, has been achieved using the palladium-catalysed reaction with phenyliodonium acetate. 3-Acyl indoles may also be prepared using acetyl chlorides with zirconium tetrachloride as a Lewis acid catalyst. 

A chemoselective O-arylation of p-keto esters was possible using copper-catalyzed reaction conditions with Li2C03 at 70 °C for a long time (Scheme 10b) [137]. The products were obtained with excellent Z-stereoselectivity independent of the substitution pattern, and cyclic p-diketones could also be employed. The observed C/O-selectivity is opposite to that found in reactions under metal-free conditions (see Sect 4.1). Heteroaiyl(phenyl)iodonium acetates were discovered as intermediates in the Pd-catalyzed acetoxylation of pyrroles and indoles mediated by DIB [83]. This feature was also exploited in the amination of various heterocycles (see Sect. 3.1.2). 

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