Altering the selectivity of metal-catalyzed borylation from C(sp2)-H to C(sp3)-H bonds without the use of directing groups is a long-standing challenge in catalysis and organic synthesis. Cobalt(II) and nickel(II) complexes supported by potentially redox-active α-diimine ligands promote the selective borylation of benzylic C(sp3)-H bonds in arenes over the more common C(sp2)-H aromatic sites (J. Am. Chem. Soc. 2016, 138, 766.; J. Am. Chem. Soc. 2017, ASAP.). Another interesting feature of this chemistry is the conversion of multiple C-H bonds on a methyl group to C-B bonds. Air stable catalyst variants have been realized and current efforts are focused on exploration of the polyborylated products in organic synthesis as well as understanding the nature of this unusual catalytic process.
Cobalt-Catalyzed C(sp2)–H Borylation with an Air-Stable, Readily Prepared Terpyridine Cobalt(II) Bis(acetate) Precatalyst
Nadia G. Léonard, Máté J. Bezdek, and Paul J. Chirik
Organometallics 2017, 36, 142-150.
Cobalt-Catalyzed C(sp2)-H Borylation: Mechanistic Insights Inspire Catalyst Design
Jennifer V. Obligacion, Scott P. Semproni, Iraklis Pappas and Paul J. Chirik
J. Am. Chem. Soc. 2016, 138, 10645-10653.
Cobalt-Catalyzed Benzylic Borylation: Enabling Polyborylation and Functionalization of Remote, Unactivated C(sp3)–H Bonds
W. Neil Palmer, Jennifer V. Obligacion, Iraklis Pappas, and Paul J. Chirik
J. Am. Chem. Soc. 2016, 138, 766-769.
Cobalt-Catalyzed C–H Borylation
Jennifer V. Obligacion, Scott P. Semproni, Paul J. Chirik
J. Am. Chem. Soc. 2014, 136 (11), 4133-4136.