scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.


2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.


2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.


2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>


2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.


2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.


2007 ◽  
Vol 2 (2) ◽  
pp. 1934578X0700200
Author(s):  
Suchitra Bhatt ◽  
Sandip K. Nayak

Anhydrous titanium(III) chloride was found to be a simple and efficient Lewis acid catalyst for ring opening of epoxides at ambient temperature. The reaction proceeded smoothly with anilines as well as azide ion as nucleophiles to give the corresponding β-amino alcohols and β-azido alcohols in moderate to good yields.


Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>


2000 ◽  
Vol 78 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Pengcheng Shao ◽  
Roland AL Gendron ◽  
David J Berg

A series of aminodiols RN(CH2CH2C(OH)Rprime2)2 (R, Rprime = Me, Me 4; Me, Ph 5; tert-butyl, Me 6; tert-Bu, Ph 7; (S)-PhCH(Me), Me 8) were prepared by the Michael addition of a primary amine to methyl acrylate followed by reaction of the resulting aminodiester with excess methyl or phenyl lithium. Reaction of two equivalents of the aminodiols 4-8 with tetrabenzylzirconium afforded the zirconium bis(aminodiolates) 10-14 in excellent yield. Complex 11 (R, Rprime = Me, Ph) adopts a cis, fac-octahedral geometry in solution and in the solid state. Complexes 10-14 are fluxional in solution by NMR spectroscopy: small substituents at nitrogen and large substituents at the alkoxide carbons slow the rate of exchange. The chiral complex 14 functions as a Lewis acid catalyst in the nitroaldol (Henry) reaction and the oxidation of geraniol by tert-butyl hydroperoxide with modest enantioselectivities (30 and 46% enantiomeric excess (ee), respectively).Key words: diol, Michael addition, zirconium, synthesis, structure, fluxional, alkoxide, Lewis acid, catalysis.


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