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31.5.1.1.18.4 Substitution of Aryl Halides

DOI: 10.1055/sos-SD-131-00281

González-Bello, C.Science of Synthesis Knowledge Updates, (20181227.

Since the pioneering work published by Buchwald and co-workers[‌47‌] in 2006 on the direct palladium-catalyzed synthesis of phenols from aryl halides (chlorides and bromides) using tris(dibenzylideneacetone)dipalladium(0) as catalyst and phosphines 19 (t-BuX-Phos) or 20 (Me4t-BuX-Phos) as ligands at elevated temperatures (80–100 °C), much effort has been devoted to the exploration of milder reaction conditions (Scheme 15). This important goal was successfully achieved by the combination of an alternative palladium precursor, (cycloocta-1,5-diene)bis(trimethylsilylmethyl)palladium(II) and the imidazole-based ligand 21. This approach allows the efficient synthesis of a variety of phenols 23 at room temperature.[‌48‌] In addition, a mixture of tris(dibenzylideneacetone)dipalladium(0) and Singer’s BippyPhos ligand 22[‌49‌] also proves to be a robust and efficient catalyst system.[‌50‌]

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