Sterically directed functionalization of aromatic C-H bonds: selective borylation ortho to cyano groups in arenes and heterocycles.
Ir-catalyzed borylations of 4-substituted benzonitriles are described. In contrast to electrophilic aromatic substitutions and directed ortho metalations, C-H activation/borylation enables functionalization at the 2-position, adjacent to the cyano group, when the 4-subsitutent is larger than cyano. When an excess of borane reagent is used, diborylation can be achieved with a single regioisomer being formed in certain cases. Extension of sterically directed borylation to cyano-substituted, five- and six-membered ring heterocycles is also reported.
Chotana
Ghayoor A
GA
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Rak
Michael A
MA
Smith
Milton R
MR
D001555:Benzene Derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D001896:Boron Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008967:Molecular Biology; D009570:Nitriles / Q000737:chemistry*; D013816:Thermodynamics
D001555:Benzene Derivatives; D001896:Boron Compounds; D006571:Heterocyclic Compounds; D009570:Nitriles; C014356:benzonitrile