ja7b02232_si_001.pdf (8.49 MB)
Ir-Catalyzed ortho-Borylation of Phenols Directed by Substrate–Ligand Electrostatic Interactions: A Combined Experimental/in Silico Strategy for Optimizing Weak Interactions
journal contribution
posted on 2017-04-28, 00:00 authored by Buddhadeb Chattopadhyay, Jonathan E. Dannatt, Ivonne L. Andujar-De Sanctis, Kristin A. Gore, Robert E. Maleczka, Daniel A. Singleton, Milton R. SmithA strategy for affecting ortho versus
meta/para selectivity in
Ir-catalyzed C–H borylations (CHBs) of phenols is described.
From selectivity observations with ArylOBpin (pin = pinacolate), it
is hypothesized that an electrostatic interaction between the partial
negatively charged OBpin group and the partial positively charged
bipyridine ligand of the catalyst favors ortho selectivity. Experimental
and computational studies designed to test this hypothesis support
it. From further computational work a second generation, in silico
designed catalyst emerged, where replacing Bpin with Beg (eg = ethylene
glycolate) was predicted to significantly improve ortho selectivity.
Experimentally, reactions employing B2eg2 gave
ortho selectivities > 99%. Adding triethylamine significantly improved
conversions. This ligand–substrate electrostatic interaction
provides a unique control element for selective C–H functionalization.