Abstract:The palladium-catalyzed coupling of amines and aryl halides or aryl alcohol derivatives has matured from an exotic small-scale transformation into a very general, efficient and robust reaction during the last ten years. This article reports several applications of this method from an industrial vantage point, including ligand synthesis, synthesis of arylpiperazines, arylhydrazines and diarylamines. Much emphasis in placed on issues of scale-up and safety to underline the potential of C À N couplings as solutions for industrial-scale synthetic problems.
A convenient, optimized and safe synthesis of N-arylhydrazines,
useful as intermediates for active ingredients in agricultural
and pharmaceutical applications, is reported. Starting from aryl
halides (chlorides and bromides), a palladium-catalyzed carbon−nitrogen coupling reaction followed by an acidic treatment
afforded the target molecules in good to excellent yields using
low catalyst loadings. This technology has then been successfully applied on a large scale in a pilot plant. This contribution
also describes the major improvements in ligand synthesis and
the thermal data required to develop a process on a pilot
scale.
Various arylhydrazones have been successfully synthesized via a highly efficient palladium-catalyzed cross-coupling reaction between aryl halides and benzophenone hydrazone. All the reaction parameters have been studied and coupling products were obtained with excellent yields from the corresponding bromides or chlorides.
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