Metal‐Free C−H Borylation of N‐Heteroarenes by Boron Trifluoride

• Published in: Chemistry : a European journal Vol. 26; no. 61; pp. 13873 - 13879
• Main Authors: Iashin, Vladimir, Berta, Dénes, Chernichenko, Konstantin, Nieger, Martin, Moslova, Karina, Pápai, Imre, Repo, Timo
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 02.11.2020; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Amines; Boron; Boron compounds; boron trifluoride; borylation; Catalysis; Chemical reactions; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Computer applications; Coupling (molecular); C−H activation; frustrated Lewis pairs; Organoboron compounds; Physical Sciences; protodeboronation; Reagents; Science & Technology; Transition metals; MECHANISM; protodeboronation; borylation; COMPLEXES; REACTIVITY; SALTS; FRUSTRATED-LEWIS-PAIR; ARENE; C-H activation; boron trifluoride; BOND ACTIVATION; GENERATION; frustrated Lewis pairs; C−H activation
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202001436

Organoboron compounds are essential reagents in modern C−C coupling reactions. Their synthesis via catalytic C−H borylation by main group elements is emerging as a powerful tool alternative to transition metal based catalysis. Herein, a straightforward metal‐free synthesis of aryldifluoroboranes from BF3 and heteroarenes is reported. The reaction is assisted by sterically hindered amines and catalytic amounts of thioureas. According to computational studies the reaction proceeds via frustrated Lewis pair (FLP) mechanism. The obtained aryldifluoroboranes are further stabilized against destructive protodeborylation by converting them to the corresponding air stable tetramethylammonium organotrifluoroborates. C−H activation: Indoles, pyrroles and indolenines undergo C−H borylation by boron trifluoride with assistance of base and thiourea additives.