American Chemical Society, ACS Central Science, 7(1), p. 394-399
DOI: 10.1021/acscentsci.5b00312
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The pyridyl group has been extensively employed to direct transition-metal-catalyzed C−H activation reactions in the past half-century. The typical cyclic transition states involved in these cyclometalation processes have only enabled the activation of ortho-C−H bonds. Here, we report that pyridine is adapted to direct meta-C−H activation of benzyl and phenyl ethyl alcohols through engineering the distance and geometry of a directing template. This template takes advantage of a stronger σ-coordinating pyridine to recruit Pd catalysts to the desired site for functionalization. The Ushaped structure accommodates the otherwise highly strained cyclophane-like transition state. This development illustrates the potential of achieving site selectivity in C−H activation via the recognition of distal and geometric relationship between existing functional groups and multiple C−H bonds in organic molecules.