Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

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.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

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.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2019 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

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.

The mechanism of 1,3-dipolar cycloaddition reactions of cyclopropanes and nitrones — A theoretical study

2005 ◽  
Vol 83 (10) ◽  
pp. 1752-1767 ◽  
Author(s):  
D Wanapun ◽  
K A Van Gorp ◽  
N J Mosey ◽  
M A Kerr ◽  
T K Woo
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Cycloaddition Reaction ◽  
Acid Catalyst ◽  
Density Functional Theory Calculations ◽  
Reaction Rates ◽  
Carbonyl Oxygen ◽  
Dipolar Cycloaddition ◽  
Similar Reaction ◽  
Lewis Acid Catalyst

The 1,3-dipolar cycloaddition reaction of cyclopropanes and nitrones to give tetrahydro-1,2-oxazine has been studied with density functional theory calculations at the B3LYP/6-31+G(d,p) level of theory. Realistic substituents were modelled including those at the 2-, 3-, 4-, and 6-positions of the final oxazine ring product. The strained σ bond of the cyclopropane was found to play the role of an alkene in a conventional [3+2] dipolar cycloaddition. Two distinct, but similar, reaction mechanisms were found — an asymmetric concerted pathway and a stepwise zwitterionic pathway. The reaction barriers of the two pathways were nearly identical, differing by less than ~1 kcal/mol, no matter what the substituents were. The effect of a Lewis acid catalyst was examined and found to have a very large effect on the calculated barriers through coordination to the carbonyl oxygen atoms of the diester substituents on the cyclopropane. The reaction barrier was found to decrease by as much as ~19 kcal/mol when using a BF3 molecule as a model for the Lewis acid catalyst. Solvent effects and the nature of the regiospecificity of the reaction were also examined. Trends in the calculated barriers for the reaction were in good agreement with available trends in the reaction rates measured experimentally. Key words: 1,3-dipolar cycloaddition, cyclopropane, nitrone, tetrahydro-1,2-oxazines, ab initio quantum chemistry, mechanism.

Synthesis and structural characterization of zirconium complexes containing aminodiolate ligands and their use as Lewis acid catalysts

2000 ◽  
Vol 78 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Pengcheng Shao ◽  
Roland AL Gendron ◽  
David J Berg
Keyword(s):  
Lewis Acid ◽  
Michael Addition ◽  
Enantiomeric Excess ◽  
Acid Catalyst ◽  
Henry Reaction ◽  
Lewis Acid Catalysts ◽  
Tert Butyl ◽  
Zirconium Complexes ◽  
Tert Butyl Hydroperoxide ◽  
Lewis Acid Catalyst

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.

scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Acid Catalyst ◽  
Catalyst Design ◽  
Lewis Acid Catalysts ◽  
Complex Molecules ◽  
New Class ◽  
Metathesis Reactions ◽  
Lewis Acid Catalyst

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.

scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Acid Catalyst ◽  
Catalyst Design ◽  
Lewis Acid Catalysts ◽  
Complex Molecules ◽  
New Class ◽  
Metathesis Reactions ◽  
Lewis Acid Catalyst

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.

scholarly journals Chiral Brønsted acid-controlled intermolecular asymmetric [2 + 2] photocycloadditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evan M. Sherbrook ◽  
Matthew J. Genzink ◽  
Bohyun Park ◽  
Ilia A. Guzei ◽  
Mu-Hyun Baik ◽  
...  
Keyword(s):  
Excited State ◽  
Lewis Acid ◽  
Photophysical Properties ◽  
Acid Catalyst ◽  
Acid Catalysts ◽  
Organic Substrates ◽  
Lewis Acid Catalysts ◽  
Lewis Acid Catalyst ◽  
Chiral Bronsted Acid ◽  
Chiral Brønsted Acids

AbstractControl over the stereochemistry of excited-state photoreactions remains a significant challenge in organic synthesis. Recently, it has become recognized that the photophysical properties of simple organic substrates can be altered upon coordination to Lewis acid catalysts, and that these changes can be exploited in the design of highly enantioselective catalytic photoreactions. Chromophore activation strategies, wherein simple organic substrates are activated towards photoexcitation upon binding to a Lewis acid catalyst, rank among the most successful asymmetric photoreactions. Herein, we show that chiral Brønsted acids can also catalyze asymmetric excited-state photoreactions by chromophore activation. This principle is demonstrated in the context of a highly enantio- and diastereoselective [2+2] photocycloaddition catalyzed by a chiral phosphoramide organocatalyst. Notably, the cyclobutane products arising from this method feature a trans-cis stereochemistry that is complementary to other enantioselective catalytic [2+2] photocycloadditions reported to date.

Thioacetalization of aldehydes and ketones in the presence of hydroxo complexes of platinum(II): An example of Lewis acid catalytic activity

2001 ◽  
Vol 79 (5-6) ◽  
pp. 621-625 ◽  
Author(s):  
Lorenzo Battaglia ◽  
Francesco Pinna ◽  
Giorgio Strukul
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Reaction Rate ◽  
Platinum Complex ◽  
Acid Catalyst ◽  
High Catalytic Activity ◽  
Hydroxo Complexes ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst

The complex [(dppb)Pt(µ-OH)]2(BF4)2 displays high catalytic activity in the thioacetalization of a variety of aldehydes and ketones with mercaptoethanol under very mild conditions. The reaction rate is greatly enhanced by the addition to the reaction mixture of magnesium perchlorate as drying agent and molar turnovers as high as 9700 can be observed. The effect of different desiccating agents is also reported. The reactivity pattern observed, the similarity with other reactions and NMR spectroscopic investigations confirm the possible role of the complex as Lewis acid catalyst in promoting the reaction.Key words: thioacetalization, catalysis, aldehydes, ketones, platinum complex.

Sign in / Sign up

Export Citation Format

Share Document