Remote site-selective C-H activation directed by a catalytic bifunctional template

Article

关键词: BOND ACTIVATION;    ASYMMETRIC CATALYSIS;    BIMETALLIC CATALYSIS;    META;    COMPLEXES;    ALKENYLATION;    SUBSTITUTION;    ALKYLATION;    ARYLATION;    LIGANDS;   

DOI  :  10.1038/nature21418

来源: SCIE

【 摘 要 】

In chemical syntheses, the activation of carbon-hydrogen (C-H) bonds converts them directly into carbon-carbon or carbonheteroatom bonds without requiring any prior functionalization. C-H activation can thus substantially reduce the number of steps involved in a synthesis. A single specific C-H bond in a substrate can be activated by using a 'directing' (usually a functional) group to obtain the desired product selectively(1-5). The applicability of such a C-H activation reaction can be severely curtailed by the distance of the C-H bond in question from the directing group, and by the shape of the substrate, but several approaches have been developed to overcome these limitations(6-12). In one such approach, an understanding of the distal and geometric relationships between the functional groups and C-H bonds of a substrate has been exploited to achieve meta-selective C-H activation by using a covalently attached, U-shaped template(13-17). However, stoichiometric installation of this template has not been feasible in the absence of an appropriate functional group on which to attach it. Here we report the design of a catalytic, bifunctional nitrile template that binds a heterocyclic substrate via a reversible coordination instead of a covalent linkage. The two metal centres coordinated to this template have different roles: one reversibly anchors substrates near the catalyst, and the other cleaves remote C-H bonds. Using this strategy, we demonstrate remote, site-selective C-H olefination of heterocyclic substrates that do not have the necessary functional groups for covalently attaching templates.

【 授权许可】

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