Aminotroponate/aminotroponiminate zinc complexes functionalized mesoporous silica catalysts for intramolecular hydroamination of non-activated alkenes with varied steric and electronic properties

Cole Duncan, Ankush V. Biradar, Teddy Asefa

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Abstract

Various aminotroponiminate-/aminotroponate-zinc complexes functionalized mesoporous silica catalysts were synthesized. These included [N-propyl-2-(propylamino)troponiminato] zinc methyl (ZnDPRT), [N-propyl-2-(phenylamino)troponiminato] zinc methyl (ZnDPHT), and [2-(propylamino)troponato] zinc methyl (ZnPRT) functionalized mesoporous silica catalysts. The catalysts were characterized by various structural (small angle XRD and gas sorption) and compositional (solid-state NMR, XPS, FTIR, and thermogravimetric and elemental analyses) techniques. Their catalytic activities for intramolecular hydroamination of nonactivated alkenes with varied steric and electronic properties were investigated. The catalysts' properties were generally found to differ from one another. This is mainly attributed to (1) fluorosilicate formation during the synthesis of the aminotroponiminate (ATI) ligands on the mesoporous silica, (2) the higher reaction efficiency of the nucleophilic substitution reaction of aminopropyl-functionalized mesoporous silica (API) with tropolone p-toluenesulfonate forming 2-(propylamino)troponato- [or aminotroponate (ATO) ligand]-functionalized sample (PRT), compared to that of the ATI ligands, where 2-(alkylamino)tropones or 2-(arylamino)tropones are activated with Et3OBF4 forming corresponding vinylgous ethers which then undergo aminolysis with the API precursor, and (3) the different compositional and structural characteristics of the amine/imine (ATI) or amine/carbonyl (ATO) chelation sites. To better understand the catalytic capabilities of the synthesized catalysts, a broader functional group compatibility study was also performed. It was found that decreased bite angles (Thorpe-Ingold effect) and increased electron donation of the p-substituted benzylic side arm of the substrates resulted in slightly increased conversion efficiencies in the hydroamination reaction. Overall, the 2,2-diphenyl cyclizing agents formed their corresponding N-containing 5-membered heterocycles at 74-94% conversion in 8 h under reflux conditions while the 2,2-dimethyl species exhibited 59-81% conversion of 12 h.

Original languageEnglish
Pages (from-to)736-750
Number of pages15
JournalACS Catalysis
Volume1
Issue number7
DOIs
Publication statusPublished - Jul 1 2011

Fingerprint

Alkenes
Silicon Dioxide
Electronic properties
Olefins
Zinc
Silica
Catalysts
Ligands
Application programming interfaces (API)
Amines
Tropolone
Imines
Ethers
Chelation
Functional groups
Conversion efficiency
Sorption
Catalyst activity
Substitution reactions
X ray photoelectron spectroscopy

Keywords

  • β-aminoalcohol
  • aminotroponiminate/aminotroponate-zinc
  • heterogeneous catalyst
  • Intramolecular hydroamination
  • mesoporous catalyst
  • non-activated alkene

ASJC Scopus subject areas

  • Catalysis

Cite this

@article{8188f35cb5244b1895502fa056f0264a,
title = "Aminotroponate/aminotroponiminate zinc complexes functionalized mesoporous silica catalysts for intramolecular hydroamination of non-activated alkenes with varied steric and electronic properties",
abstract = "Various aminotroponiminate-/aminotroponate-zinc complexes functionalized mesoporous silica catalysts were synthesized. These included [N-propyl-2-(propylamino)troponiminato] zinc methyl (ZnDPRT), [N-propyl-2-(phenylamino)troponiminato] zinc methyl (ZnDPHT), and [2-(propylamino)troponato] zinc methyl (ZnPRT) functionalized mesoporous silica catalysts. The catalysts were characterized by various structural (small angle XRD and gas sorption) and compositional (solid-state NMR, XPS, FTIR, and thermogravimetric and elemental analyses) techniques. Their catalytic activities for intramolecular hydroamination of nonactivated alkenes with varied steric and electronic properties were investigated. The catalysts' properties were generally found to differ from one another. This is mainly attributed to (1) fluorosilicate formation during the synthesis of the aminotroponiminate (ATI) ligands on the mesoporous silica, (2) the higher reaction efficiency of the nucleophilic substitution reaction of aminopropyl-functionalized mesoporous silica (API) with tropolone p-toluenesulfonate forming 2-(propylamino)troponato- [or aminotroponate (ATO) ligand]-functionalized sample (PRT), compared to that of the ATI ligands, where 2-(alkylamino)tropones or 2-(arylamino)tropones are activated with Et3OBF4 forming corresponding vinylgous ethers which then undergo aminolysis with the API precursor, and (3) the different compositional and structural characteristics of the amine/imine (ATI) or amine/carbonyl (ATO) chelation sites. To better understand the catalytic capabilities of the synthesized catalysts, a broader functional group compatibility study was also performed. It was found that decreased bite angles (Thorpe-Ingold effect) and increased electron donation of the p-substituted benzylic side arm of the substrates resulted in slightly increased conversion efficiencies in the hydroamination reaction. Overall, the 2,2-diphenyl cyclizing agents formed their corresponding N-containing 5-membered heterocycles at 74-94{\%} conversion in 8 h under reflux conditions while the 2,2-dimethyl species exhibited 59-81{\%} conversion of 12 h.",
keywords = "β-aminoalcohol, aminotroponiminate/aminotroponate-zinc, heterogeneous catalyst, Intramolecular hydroamination, mesoporous catalyst, non-activated alkene",
author = "Cole Duncan and Biradar, {Ankush V.} and Teddy Asefa",
year = "2011",
month = "7",
day = "1",
doi = "10.1021/cs2000945",
language = "English",
volume = "1",
pages = "736--750",
journal = "ACS Catalysis",
issn = "2155-5435",
publisher = "American Chemical Society",
number = "7",

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TY - JOUR

T1 - Aminotroponate/aminotroponiminate zinc complexes functionalized mesoporous silica catalysts for intramolecular hydroamination of non-activated alkenes with varied steric and electronic properties

AU - Duncan, Cole

AU - Biradar, Ankush V.

AU - Asefa, Teddy

PY - 2011/7/1

Y1 - 2011/7/1

N2 - Various aminotroponiminate-/aminotroponate-zinc complexes functionalized mesoporous silica catalysts were synthesized. These included [N-propyl-2-(propylamino)troponiminato] zinc methyl (ZnDPRT), [N-propyl-2-(phenylamino)troponiminato] zinc methyl (ZnDPHT), and [2-(propylamino)troponato] zinc methyl (ZnPRT) functionalized mesoporous silica catalysts. The catalysts were characterized by various structural (small angle XRD and gas sorption) and compositional (solid-state NMR, XPS, FTIR, and thermogravimetric and elemental analyses) techniques. Their catalytic activities for intramolecular hydroamination of nonactivated alkenes with varied steric and electronic properties were investigated. The catalysts' properties were generally found to differ from one another. This is mainly attributed to (1) fluorosilicate formation during the synthesis of the aminotroponiminate (ATI) ligands on the mesoporous silica, (2) the higher reaction efficiency of the nucleophilic substitution reaction of aminopropyl-functionalized mesoporous silica (API) with tropolone p-toluenesulfonate forming 2-(propylamino)troponato- [or aminotroponate (ATO) ligand]-functionalized sample (PRT), compared to that of the ATI ligands, where 2-(alkylamino)tropones or 2-(arylamino)tropones are activated with Et3OBF4 forming corresponding vinylgous ethers which then undergo aminolysis with the API precursor, and (3) the different compositional and structural characteristics of the amine/imine (ATI) or amine/carbonyl (ATO) chelation sites. To better understand the catalytic capabilities of the synthesized catalysts, a broader functional group compatibility study was also performed. It was found that decreased bite angles (Thorpe-Ingold effect) and increased electron donation of the p-substituted benzylic side arm of the substrates resulted in slightly increased conversion efficiencies in the hydroamination reaction. Overall, the 2,2-diphenyl cyclizing agents formed their corresponding N-containing 5-membered heterocycles at 74-94% conversion in 8 h under reflux conditions while the 2,2-dimethyl species exhibited 59-81% conversion of 12 h.

AB - Various aminotroponiminate-/aminotroponate-zinc complexes functionalized mesoporous silica catalysts were synthesized. These included [N-propyl-2-(propylamino)troponiminato] zinc methyl (ZnDPRT), [N-propyl-2-(phenylamino)troponiminato] zinc methyl (ZnDPHT), and [2-(propylamino)troponato] zinc methyl (ZnPRT) functionalized mesoporous silica catalysts. The catalysts were characterized by various structural (small angle XRD and gas sorption) and compositional (solid-state NMR, XPS, FTIR, and thermogravimetric and elemental analyses) techniques. Their catalytic activities for intramolecular hydroamination of nonactivated alkenes with varied steric and electronic properties were investigated. The catalysts' properties were generally found to differ from one another. This is mainly attributed to (1) fluorosilicate formation during the synthesis of the aminotroponiminate (ATI) ligands on the mesoporous silica, (2) the higher reaction efficiency of the nucleophilic substitution reaction of aminopropyl-functionalized mesoporous silica (API) with tropolone p-toluenesulfonate forming 2-(propylamino)troponato- [or aminotroponate (ATO) ligand]-functionalized sample (PRT), compared to that of the ATI ligands, where 2-(alkylamino)tropones or 2-(arylamino)tropones are activated with Et3OBF4 forming corresponding vinylgous ethers which then undergo aminolysis with the API precursor, and (3) the different compositional and structural characteristics of the amine/imine (ATI) or amine/carbonyl (ATO) chelation sites. To better understand the catalytic capabilities of the synthesized catalysts, a broader functional group compatibility study was also performed. It was found that decreased bite angles (Thorpe-Ingold effect) and increased electron donation of the p-substituted benzylic side arm of the substrates resulted in slightly increased conversion efficiencies in the hydroamination reaction. Overall, the 2,2-diphenyl cyclizing agents formed their corresponding N-containing 5-membered heterocycles at 74-94% conversion in 8 h under reflux conditions while the 2,2-dimethyl species exhibited 59-81% conversion of 12 h.

KW - β-aminoalcohol

KW - aminotroponiminate/aminotroponate-zinc

KW - heterogeneous catalyst

KW - Intramolecular hydroamination

KW - mesoporous catalyst

KW - non-activated alkene

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U2 - 10.1021/cs2000945

DO - 10.1021/cs2000945

M3 - Article

VL - 1

SP - 736

EP - 750

JO - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

IS - 7

ER -