Phosphine‐Directed CH Borylation Reactions: Facile and Selective Access to Ambiphilic Phosphine Boronate Esters

Abstract

Ambiphilic ligands have received considerable attention over the last two decades due to their unique reactivity as organocatalysts and ligands. The iridium-catalyzed C-H borylation of phosphines is described in which the phosphine is used as a directing group to provide selective formation of arylboronate esters with unique scaffolds of ambiphilic compounds. A variety of aryl and benzylic phosphines were subjected to the reaction conditions, selectively providing stable, isolable boronate esters upon protection of the phosphine as the borane complex. After purification, the phosphine-substituted boronate esters could be deprotected and isolated in pure form.

RhI‐Catalyzed PIII‐Directed C−H Bond Alkylation: Design of Multifunctional Phosphines for Carboxylation of Aryl Bromides with Carbon Dioxide

“…In 2014, Clark et al demonstrated that P III could act as ad irecting group in Ir I -catalyzed CÀHb ond borylation of JohnPhos derivatives. [11] In 2019, Takayasa nd Shisg roups independently reported the ortho-borylation of triarylphosphines using Ru II or Rh I catalysis. [12] In 2017, Shisg roup reported the Rh I -catalyzed CÀHb ond arylation of biarylphosphines at the ortho' position, thus offering efficient access to triarylphosphines.…”

RhI‐Catalyzed PIII‐Directed C−H Bond Alkylation: Design of Multifunctional Phosphines for Carboxylation of Aryl Bromides with Carbon Dioxide

“…[9] However,i nm ost of the cases,t he phosphorus atom has to be oxidized to act as aP V directing group. [11] In 2019, Takayasa nd Shisg roups independently reported the ortho-borylation of triarylphosphines using Ru II or Rh I catalysis. In 2014, Clark et al demonstrated that P III could act as ad irecting group in Ir I -catalyzed CÀHb ond borylation of JohnPhos derivatives.…”

Enantioselective Borylation of Aromatic C−H Bonds with Chiral Dinitrogen Ligands

“…[2e, 4] However, most directing groups are difficult to remove after the introduction of the boryl group. To address this issue, our group developed silyl-directed borylations of C-H bonds (Scheme 1c).…”

“…Because rhodium complexes containing phosphines also catalyze the borylation of aromatic C-H bonds, [3c, 4d] we tested various combinations of rhodium precursors and chiral phosphines as catalyst for the enantioselective borylation (for details, see Supporting Information). However, no conversion was observed for reactions conducted with any of the rhodium catalysts generated from [Rh(cod)Cl] 2 and chiral bisphosphine ligands.…”