Palladium Catalysts for Highly Selective Sonogashira Reactions of Aryl and Heteroaryl Bromides

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Abstract

Palladium catalysts have been studied for the Sonogashira–Hagihara coupling of aryl and heteroaryl bromides with terminal alkynes. Among the different biarylphosphines tested, 2-(di-tert-butylphosphino)-N-phenylindole (cataCXium PIntb) allows the efficient coupling of both activated and deactivated (hetero)aryl bromides in the presence of sodium tetrachloropalladate in tetramethylethylenediamine (TMEDA) at 80 °C. The catalyst system gives high turnover numbers (up to 14 100) and shows a broad tolerance towards functional groups such as OH and NH2, as well as heterocycles.

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