Arylamines are ubiquitous building blocks for various dyes, fine chemicals, electronic materials, and among the most prevalent structural motifs in pharmaceutical agents. Consequently, continuing efforts have been made to develop new and effective approaches for the formation of aryl amines throughout the history of organic chemistry. Among the various methods, the most prominent reactions are the transition-metal catalyzed coupling of aryl halides with amines. However, the need of pre-synthesizing the aryl halides and the generation of unwanted halide waste in the end are the drawbacks of aryl halide based strategies.<br/> <br/>On the other hand, phenols (mostly in its polymeric forms in lignin and coal) are the second most prevalent naturally occurring structural units of renewable biomass on the planet, and have the same oxidation state as haloarenes. Thus, the direct coupling of phenols, instead of the haloarenes, has long been a synthetic aspiration and great scientific challenge.  However, previous methods requires the transformation of phenol hydroxyl groups first to a better leaving group, and then couple with amine through transition-metal catalysis, which increase number of steps and waste. Herein, we present a highly efficient, palladium-catalyzed direct coupling of phenols with various amines and anilines.  A variety of substituted phenols were compatible with this method.

Principle 9. Catalysis: Catalytic coupling of phenol without using coupling reaction

255th National Meeting (2018)

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