Oxidative coupling palladium pivalate

To date, only one report has referred to the direct allqmylation of indoles under aerobic conditions. In 2010, Li and co-workers described a palladium-catalyzed oxidative coupling of 1,3-dimethylindoles with phenylacetylenes." Using a buffer system composed of 20 mol% cesium carbonate and 2 equiv. pivalic acid at 80 °C, the desired cross-coupling products were obtained in moderate-to-good yields (Scheme 9.21). 

O/t/20-arylation of benzoic acids is often preferable to ortho-arylation of benzamides if conversion of the amide moiety to other functional groups is desired. However, only a few reports have dealt with the orf/io-functionalization of free benzoic acids due to challenges that involve such transformations. The reactions can be complicated by decarboxylation of the product and the starting material. Despite those difficulties, several methods for direct o/t/io-arylation of benzoic acids have been developed. Yu has shown that arylboronates are effective in arylation of benzoic acids under palladium catalysis [59], The reactions require the presence of palladium acetate catalyst, silver carbonate oxidant, and benzoquinone. Even more interestingly, the procedure is applicable to the arylation of unactivated sp3 C-H bonds in tertiary carboxylic acids such as pivalic acid (Scheme 13) if aryl iodide coupling partner is used. Aryl trifluoroborates can also be used [60],... 

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