Issue Date: July 24, 2006
NH3's synthetic appeal gets a boost
Ammonia is cheap and plentiful but rarely used as a reagent in catalytic processes. In hopes of broadening the synthetic appeal of this atom-economical nitrogen source, Yale University chemists have used NH3 in a catalytic process to make primary aromatic amines, an important class of chemical building blocks (J. Am. Chem. Soc., DOI: 10.1021/ja064005t). John F. Hartwig and Qilong Shen use NH3 and a palladium catalyst bearing the commercial Josiphos ligand (shown) to convert aryl halides into primary arylamines. Previous palladium-catalyzed syntheses of primary arylamines have relied on ammonia surrogates. The catalytic system Hartwig and Shen report affords good yields and excellent selectivity with NH3, but they will have to overcome a number of hurdles for the reaction to find commercial use, including lowering catalyst loads, reducing dilution requirements, and increasing functional group tolerance. That quest will be helped by further study of the reaction's mechanism, which involves a never-before-seen C-N bond-forming reductive elimination of an NH2 complex, the authors report.
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