Organometallic Lewis acids. 28. Directed synthesis of .sigma.,.pi.-allyl-bridged metal compounds via nucleophilic attack of carbonylmetalates to cationic .pi.-allyl complexes (.eta.5-C5H5)(OC)(ON)Mo(.sigma.,.pi.-allyl)M(CO)5 (M = Re, Mn)

Hans Joachim. Mueller; Ulrich. Nagel; Wolfgang. Beck

doi:10.1021/om00144a037

Organometallic Lewis Acids, Part LVIIII [1]. Directed Synthesis of Dinuclear Metal Carbonyl Complexes of Rhenium, Iron, Chromium, and Tungsten with a Single Unsupported Halide or Pseudohalide Bridge (Cl-, Br-, I-, CN-, C(CN)3-, NCS-, PPh2-, SH-) by Use of Re(CO)5FBF3

Zeitschrift für Naturforschung B ◽

10.5560/znb.2014-4095 ◽

2014 ◽

Vol 69 (11-12) ◽

pp. 1215-1220

Author(s):

Peter M. Fritz ◽

Wolfgang Sacher ◽

Wolfgang Beck

Keyword(s):

Lewis Acids ◽

Metal Carbonyl ◽

Carbonyl Complexes ◽

Metal Carbonyl Complexes ◽

Directed Synthesis ◽

Iron Chromium ◽

And Tungsten

Abstract By use of Re(CO)5FBF3 the complexes with a single unsupported halide or pseudohalide bridge [Cp(OC)2Fe-X-Re(CO)5]+ BF4- (X=Cl, I, PPh2), (OC)5M-X-Re(CO)5 (M=Cr, W; X=Br, I, CN, NCS, SH), (OC)5W-N≡C-C[-C≡N-Re(CO)5]2+ BF4-, Cp(OC)(NC)Fe-C≡N-Re(CO)5, and [(OC)5Re-N3-Re(CO)5]+ BF4- have been synthesized.

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Reactions of β-diketone compounds with nitriles catalyzed by Lewis acids: a simple approach to β-enaminone synthesis

RSC Advances ◽

10.1039/c4ra10879e ◽

2014 ◽

Vol 4 (109) ◽

pp. 63897-63900 ◽

Cited By ~ 11

Author(s):

Xu Cheng ◽

Shuchen Pei ◽

Chenchen Xue ◽

Kaifei Cao ◽

Li Hai ◽

...

Keyword(s):

Lewis Acids ◽

Simple Approach ◽

Aluminium Chloride ◽

Nucleophilic Attack

Aluminium chloride selectively promoted the nucleophilic attack of β-diketone compounds with nitriles to give enaminones.

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Role of Lewis Acids in Preventing the Degradation of Dithioester-Dormant Species in the RAFT Polymerization of Acrylamides in Methanol to Enable the Successful Dual Control of Molecular Weight and Tacticity

10.26434/chemrxiv.14622915 ◽

2021 ◽

Author(s):

Yuji Imamura ◽

Shigeru Yamago

Keyword(s):

Molecular Weight ◽

Lewis Acids ◽

Chain Transfer ◽

Raft Polymerization ◽

Degradation Mechanism ◽

Earth Metal ◽

Nucleophilic Attack ◽

Molecular Weights ◽

Reversible Addition ◽

Metal Triflates

Reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylamide in methanol using dithioester RAFT chain-transfer agents was unsuccessful due to degradation of the end group. However, this degradation was completely suppressed by the addition of rare-earth metal triflates (RMTs). As RMTs are effective for the stereoselective polymerization of acrylamides, RAFT polymerization in the presence of RMTs afforded the corresponding poly(acrylamide)s with controlled molecular weight and tacticity. The conditions allowed the synthesis of high-molecular-weight polyacrylamides with molecular weights up to 168,000, low dispersity (<1.5) and high tacticity (90% meso diad selectivity). The degradation mechanism initiated by nucleophilic attack of acrylamide on the dithioester group was experimentally clarified for the first time. As RMT is a Lewis acid, its coordination to the amide group of acrylamide reduces its nucleophilicity.

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Role of Lewis Acids in Preventing the Degradation of Dithioester-Dormant Species in the RAFT Polymerization of Acrylamides in Methanol to Enable the Successful Dual Control of Molecular Weight and Tacticity

10.26434/chemrxiv.14622915.v1 ◽

2021 ◽

Author(s):

Yuji Imamura ◽

Shigeru Yamago

Keyword(s):

Molecular Weight ◽

Lewis Acids ◽

Chain Transfer ◽

Raft Polymerization ◽

Degradation Mechanism ◽

Earth Metal ◽

Nucleophilic Attack ◽

Molecular Weights ◽

Reversible Addition ◽

Metal Triflates

Reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylamide in methanol using dithioester RAFT chain-transfer agents was unsuccessful due to degradation of the end group. However, this degradation was completely suppressed by the addition of rare-earth metal triflates (RMTs). As RMTs are effective for the stereoselective polymerization of acrylamides, RAFT polymerization in the presence of RMTs afforded the corresponding poly(acrylamide)s with controlled molecular weight and tacticity. The conditions allowed the synthesis of high-molecular-weight polyacrylamides with molecular weights up to 168,000, low dispersity (<1.5) and high tacticity (90% meso diad selectivity). The degradation mechanism initiated by nucleophilic attack of acrylamide on the dithioester group was experimentally clarified for the first time. As RMT is a Lewis acid, its coordination to the amide group of acrylamide reduces its nucleophilicity.

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Asymmetric synthesis based on chiral (arene)tricarbonylchromium acetal complexes. Addition reactions to the ortho-formyl complex

Canadian Journal of Chemistry ◽

10.1139/v00-150 ◽

2000 ◽

Vol 78 (12) ◽

pp. 1629-1636 ◽

Cited By ~ 5

Author(s):

M Kevin McKay ◽

James R Green

Keyword(s):

Asymmetric Synthesis ◽

Lewis Acid ◽

Lewis Acids ◽

Nucleophilic Attack ◽

Addition Reactions ◽

Trans Conformation ◽

Enantiomerically Pure ◽

The Face ◽

Monodentate Coordination ◽

Tricarbonylchromium Complexes

The addition reactions of organolithium and Grignard reagents to chiral, enantiomerically pure ortho-formyl (arene)tricarbonylchromium acetal complex (2) have been studied. The diastereoselectivity of the addition process is fair in the absence of an additional Lewis acid, and good in the presence of Ti(OiPr)4. The nature of the newly formed chiral centre, and studies on the possible nature of the nucleophilic species suggest that the Lewis acid acts through monodentate coordination to the aldehyde carbonyl, and thereby alters the carbonyl rotamer population more heavily in favour of the s-trans conformation. Nucleophilic attack then occurs on the face anti- to that bearing the Cr(CO)3 unit.Key words: (arene)tricarbonylchromium complexes, asymmetric synthesis, carbonyl additions, Lewis acids.

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Directed synthesis of bimetallic hydrocarbon bridged compounds by nucleophilic attack of carbonyl metalates on coordinated unsaturated hydrocarbons

Polyhedron ◽

10.1016/s0277-5387(00)86342-1 ◽

1988 ◽

Vol 7 (22-23) ◽

pp. 2255-2261 ◽

Cited By ~ 38

Author(s):

Wolfgang Beck

Keyword(s):

Nucleophilic Attack ◽

Unsaturated Hydrocarbons ◽

Directed Synthesis

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Amphoteric Lewis Acid/base Activity Enables an Unprecedented Pathway for Low-Energy C-O Cleavage in the Electrocatalytic Reduction of Carbon Dioxide

10.26434/chemrxiv.14035625 ◽

2021 ◽

Author(s):

Hemlata Agarwala ◽

Xiaoyu Chen ◽

Julien R. Lyonnet ◽

Ben A Johnson ◽

Mårten Ahlquist ◽

...

Keyword(s):

Lewis Acid ◽

Lewis Acids ◽

Density Functional ◽

Activation Barrier ◽

Bond Cleavage ◽

Lewis Base ◽

Nucleophilic Attack ◽

Co Conversion ◽

Energy Conserving ◽

Ft Ir

Molecular electrocatalysts for CO2-to-CO conversion often operate at large overpotentials, the cleavage of C-O bond in the intermediate largely contributing to this phenomenon. Additional Lewis acids have been shown to aid in weakening the C-O bond. We herein present computational and experimental evidence, with ruthenium polypyridyl based CO2 reduction electrocatalysts, for a mechanistic route that involves one metal center acting as both Lewis base and Lewis acid at different stages of the catalytic cycle. The Lewis basic character of Ru is seen in the initial nucleophilic attack at CO2 to form [Ru-CO2]0, while its Lewis acid character allows the formation of a 5-membered metallacyclic intermediate, [Ru-CO2CO2]0,c, by intramolecular cyclization of a linear [Ru-CO2CO2]0 species that is formed from [Ru-CO2]0 and a second equivalent of CO2. [Ru-CO2CO2]0,c is crucial for energy-conserving turnover, as it allows for a third reduction at a more positive potential than that of the starting complex Ru2+. The calculated activation barrier for C-O bond cleavage in [Ru-CO2CO2]-1,c is dramatically decreased to 10.5 kcal mol-1 from 60 kcal mol-1, the latter required for C-O bond cleavage in the linear intermediate [Ru-CO2CO2]0. The intermediates are characterized experimentally by FT-IR and 13C NMR spectroscopy during electrocatalytic turnover and are corroborated by density functional theory (DFT).

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Recent Advances in Denitrogenative Reactions of Pyridotriazoles

Synthesis ◽

10.1055/s-0040-1707254 ◽

2020 ◽

Vol 52 (23) ◽

pp. 3564-3576 ◽

Cited By ~ 1

Author(s):

Ilya P. Filippov ◽

Gleb D. Titov ◽

Nikolai V. Rostovskii

Keyword(s):

Lewis Acids ◽

Heterocyclic Compounds ◽

Short Review ◽

Diazo Compounds ◽

Metal Compounds ◽

The Past ◽

Recent Advances ◽

Catalyzed Reactions ◽

Metal Catalyzed ◽

Chain Isomerization

AbstractDiazo compounds display versatile reactivity and therefore are widely used in organic synthesis. Diazo compounds bearing a 2-pyridyl or a related azine moiety on the diazo carbon exist in the form of fused 1,2,3-triazoles. In this short review, we summarize the recent advances in denitrogenative reactions of [1,2,3]triazolo[1,5-a]pyridines (‘pyridotriazoles’) and related fused 1,2,3-triazoles. Over the past decade, there has been a surge of activity in this field, with novel denitrogenative reactions of pyridotriazoles induced by metal compounds, light, and Brønsted and Lewis acids having been devised. As a result, heterocyclic compounds and functionalized α-picolines as well as bioactive molecules have been synthesized. In the review, emphasis is also placed on the mechanisms of the new reactions.1 Introduction2 Ring-Chain Isomerization of Pyridotriazoles3 Metal-Catalyzed Reactions3.1 Rh(II) Catalysis3.2 Rh(III) Catalysis3.3 Cu Catalysis3.4 Pd Catalysis3.5 Catalysis by Other Metals4 Metal-Free Reactions5 Conclusion

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ChemInform Abstract: Organometallic Lewis Acids. Part 24. Directed Synthesis of Rhenamolybdatetrahedranes: Nucleophilic Addition of Pentacarbonylrhenate(1-) to Alkyne Ligands in Cationic Molybdenum Complexes.

ChemInform ◽

10.1002/chin.198701265 ◽

1987 ◽

Vol 18 (1) ◽

Author(s):

W. BECK ◽

H.-J. MUELLER ◽

U. NAGEL

Keyword(s):

Nucleophilic Addition ◽

Lewis Acids ◽

Molybdenum Complexes ◽

Directed Synthesis

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Amphoteric Lewis Acid/base Activity Enables an Unprecedented Pathway for Low-Energy C-O Cleavage in the Electrocatalytic Reduction of Carbon Dioxide

10.26434/chemrxiv.14035625.v1 ◽

2021 ◽

Author(s):

Hemlata Agarwala ◽

Xiaoyu Chen ◽

Julien R. Lyonnet ◽

Ben A Johnson ◽

Mårten Ahlquist ◽

...

Keyword(s):

Lewis Acid ◽

Lewis Acids ◽

Density Functional ◽

Activation Barrier ◽

Bond Cleavage ◽

Lewis Base ◽

Nucleophilic Attack ◽

Co Conversion ◽

Energy Conserving ◽

Ft Ir

Molecular electrocatalysts for CO2-to-CO conversion often operate at large overpotentials, the cleavage of C-O bond in the intermediate largely contributing to this phenomenon. Additional Lewis acids have been shown to aid in weakening the C-O bond. We herein present computational and experimental evidence, with ruthenium polypyridyl based CO2 reduction electrocatalysts, for a mechanistic route that involves one metal center acting as both Lewis base and Lewis acid at different stages of the catalytic cycle. The Lewis basic character of Ru is seen in the initial nucleophilic attack at CO2 to form [Ru-CO2]0, while its Lewis acid character allows the formation of a 5-membered metallacyclic intermediate, [Ru-CO2CO2]0,c, by intramolecular cyclization of a linear [Ru-CO2CO2]0 species that is formed from [Ru-CO2]0 and a second equivalent of CO2. [Ru-CO2CO2]0,c is crucial for energy-conserving turnover, as it allows for a third reduction at a more positive potential than that of the starting complex Ru2+. The calculated activation barrier for C-O bond cleavage in [Ru-CO2CO2]-1,c is dramatically decreased to 10.5 kcal mol-1 from 60 kcal mol-1, the latter required for C-O bond cleavage in the linear intermediate [Ru-CO2CO2]0. The intermediates are characterized experimentally by FT-IR and 13C NMR spectroscopy during electrocatalytic turnover and are corroborated by density functional theory (DFT).

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