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Friedel–Crafts Benzylation of Activated and Deactivated Arenes


  • This work was supported by ETH Research Grant ETH-12 11-1. We thank the ETH Zürich Mass Spectrometry Service for spectroscopic data, Aaron Dumas for helpful discussions, and Cam-Van Thi Vo for a preliminary study.


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NO going back makes possible facile Friedel–Crafts benzylations with moderate reaction temperatures, simple reaction workups, and improved substrate scope for the formation of synthetically important diarylmethanes (see scheme). Upon complexation with BF3⋅OEt2, hydroxamates serve as reversible leaving groups that stabilize highly reactive carbocations. Even deactivated arenes and electron-deficient benzylhydroxamates react cleanly under these conditions.