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Article
Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration
ACS Catalysis
  • Naresh Eedugurala, Iowa State University
  • Zhuoran Wang, Iowa State University
  • Umesh Chaudhary, Iowa State University
  • Nicholas C. Nelson, Iowa State University
  • Kapil Kandel, Iowa State University
  • Takeshi Kobayashi, Iowa State University
  • Igor I. Slowing, Iowa State University
  • Marek Pruski, Iowa State University
  • Aaron D. Sadow, Iowa State University
Document Type
Article
Disciplines
Publication Version
Published Version
Publication Date
11-4-2015
DOI
10.1021/acscatal.5b01671
Abstract

The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. Thus, these supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.

Comments

Reprinted (adapted) with permission from ACS Catalysis 5 (2015): 7399, doi: 10.1021/acscatal.5b01671. Copyright 2015 American Chemical Society.

Copyright Owner
American Chemical society
Language
en
File Format
application/pdf
Citation Information
Naresh Eedugurala, Zhuoran Wang, Umesh Chaudhary, Nicholas C. Nelson, et al.. "Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration" ACS Catalysis Vol. 5 (2015) p. 7399 - 7414
Available at: http://works.bepress.com/aaron_sadow/27/