+Cations: Chloroborane Masked Chiral Borenium Ions
Journal
Inorganic Chemistry
Journal Volume
60
Journal Issue
21
Pages
16266-16272
Date Issued
2021
Author(s)
Abstract
A tricoordinate borenium ion has received considerable attention in recent years for its applications in Lewis acid catalysis. Over the years, asymmetric catalysis mediated by a chiral borenium ion has also been developed. To stabilize the electron-deficient boron atom, a series of chloroborane masked borenium ions featuring the symmetrical [B-Cl-B]+ linkage are prepared and utilized as the catalyst for the enantioselective Diels-Alder cycloaddition of cyclopentadiene and 2,2,2-trifluoroethyl acrylate. The presence of a Cp? ligand is critical in realizing the cyclic diboron compounds, and the stability of the resulting [B-Cl-B]+ cation is dependent on the steric bulkiness of the oxazolidinone moiety. The stereoselectivity of the Diels-Alder cycloaddition is controlled by the substituents of the chiral oxazolidinone ligand and could be further improved via the coordination of SnCl4 at the bridging chloride of the [B-Cl-B]+ cation. ? 2021 American Chemical Society.
Subjects
Catalysis
Chlorine compounds
Cycloaddition
Ligands
Tin compounds
Asymmetric catalysis
Boron atom
Cp* ligand
Cyclopentadienes
Diels-Alder cycloadditions
Electron-deficient
Enantioselective
ITS applications
Lewis acid catalysis
]+ catalyst
Positive ions
SDGs
Type
journal article