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Published on: May 21, 2019
Transient π-coordination enables nucleophilic borylation of simple arenes
Yuichiro Mutoh1, Relam Khalaf1,2, Sobi Asako1
1RIKEN Center for Sustainable Resource Science 2-1 Hirosawa, Wako Saitama 351-0198 Japan yuichiro.mutoh@riken.jp laurean.ilies@riken.jp.
None:
Borylation of an arene typically proceeds via transition-metal-catalyzed C-H activation. We report here that transient π-coordination to chromium activates 1 equiv. of a simple arene towards nucleophilic borylation with B2(pin)2 in the presence of an additive such as K2CO3 or KF. The transient activation of the substrate is achieved via in situ ligand exchange with a naphthalene chromium complex, followed by borylation of the resulting arene chromium complex. Electron-rich and sterically hindered arenes, challenging substrates for transition-metal-catalyzed C-H borylation, react well under these conditions. Mechanistic studies support an anionic mechanism, where a borate species undergoes nucleophilic addition to the arene chromium complex, followed by hydride migration.
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