Suzuki inert atmosphere

Either thallium(l) hydroxide or thallium(l) ethoxide as a base substantially promotes the couphng of aryl and vinyl halides with organic boronic acids (Suzuki coupling) (Schemes 9.86 [84], 9.87 [85], 9.88 [86], 9.89 [87], 9.90 [88], 9.91 [89], and 9.92 [90]). Both reagents are air- and moisture-sensitive, HOEt being significantly more stable than TlOH, and should be handled under an inert atmosphere. Unfortunately, these reactions are not catalytic in thallium and excess thalhum salt (2-3 equiv.) relative to the halide is necessary. 

While phosphine-ligated catalysts like 77 and 81 are effective in thermo-morphic systems, the oxidation of phosphine ligands in the presence of transition metal compounds and especially in the presence of Pd(0) poses experimental and practical problems in recycling catalysts in batch reactions. Such issues can be handled with more rigorous inert atmosphere equipment. Alternatively, more stable catalysts can be used. In the case of Heck and Suzuki chemistry, very stable pincer-type catalysts are available. These include phosphine-ligated species like 112 and thioether-ligated species like 113 [152-154]. 

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