Synthesis, Structure, and Reactivity of Anionic sp2–sp3 Diboron Compounds: Readily Accessible Boryl Nucleophiles
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- 15 April 2015
- journal article
- research article
- Published by Wiley in Chemistry – A European Journal
- Vol. 21 (19) , 7082-7098
Abstract
Lewis base adducts of tetra‐alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2pin2), have been proposed as the active source of nucleophilic boryl species in metal‐free borylation reactions. We report the isolation and detailed structural characterization (by solid‐state and solution NMR spectroscopy and X‐ray crystallography) of a series of anionic adducts of B2pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp2)–B(sp3) adducts exhibit two distinct boron environments in the solid‐state and solution NMR spectra, except for [(4‐tBuC6H4O)B2pin2]−, which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles—namely, aryl halides and diazonium salts—demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources.Keywords
This publication has 158 references indexed in Scilit:
- Synthesis of a bicyclic diborane by selective boron carbon bond formationChemical Communications, 2013
- Metal-Free Catalytic Enantioselective C–B Bond Formation: (Pinacolato)boron Conjugate Additions to α,β-Unsaturated Ketones, Esters, Weinreb Amides, and Aldehydes Promoted by Chiral N-Heterocyclic CarbenesJournal of the American Chemical Society, 2012
- Spectroscopic and Structural Characterization of the CyNHC Adduct of B2pin2 in Solution and in the Solid StateThe Journal of Organic Chemistry, 2011
- Metal-Free Catalytic C–Si Bond Formation in an Aqueous Medium. Enantioselective NHC-Catalyzed Silyl Conjugate Additions to Cyclic and Acyclic α,β-Unsaturated CarbonylsJournal of the American Chemical Society, 2011
- Enantioselective Synthesis of Boron-Substituted Quaternary Carbons by NHC−Cu-Catalyzed Boronate Conjugate Additions to Unsaturated Carboxylic Esters, Ketones, or ThioestersJournal of the American Chemical Society, 2010
- α-Selective Ni-Catalyzed Hydroalumination of Aryl- and Alkyl-Substituted Terminal Alkynes: Practical Syntheses of Internal Vinyl Aluminums, Halides, or BoronatesJournal of the American Chemical Society, 2010
- Synthesis and Structure of a Carbene‐Stabilized π‐Boryl AnionAngewandte Chemie International Edition, 2010
- Synthese und Struktur eines Carben‐stabilisierten π‐Boryl‐AnionsAngewandte Chemie, 2010
- Efficient C−B Bond Formation Promoted by N-Heterocyclic Carbenes: Synthesis of Tertiary and Quaternary B-Substituted Carbons through Metal-Free Catalytic Boron Conjugate Additions to Cyclic and Acyclic α,β-Unsaturated CarbonylsJournal of the American Chemical Society, 2009
- A short history of SHELXActa Crystallographica Section A Foundations of Crystallography, 2007