Lewis Base Activation of Lewis Acids:  Development of a Lewis Base Catalyzed Selenolactonization

2007 ◽  
Vol 9 (19) ◽  
pp. 3801-3804 ◽  
Author(s):  
Scott E. Denmark ◽  
William R. Collins
Keyword(s):  
Lewis Acids ◽  
Lewis Base

Lewis Base Activation of Lewis Acids. Addition of Silyl Ketene Acetals to Aldehydes

2002 ◽  
Vol 124 (45) ◽  
pp. 13405-13407 ◽  
Author(s):  
Scott E. Denmark ◽  
Thomas Wynn ◽  
Gregory L. Beutner
Keyword(s):  
Lewis Acids ◽  
Lewis Base ◽  
Ketene Acetals ◽  
Silyl Ketene Acetals

scholarly journals The Nature of Triel Bonds, a Case of B and Al Centres Bonded with Electron Rich Sites

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2703 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Lewis Acids ◽  
Weak Interactions ◽  
Lewis Base ◽  
Basis Set ◽  
Strong Interactions ◽  
Orbital Method ◽  
Covalent Bonds ◽  
Moller Plesset ◽  
Intermolecular Distances ◽  
Base Units

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed on complexes of triel species: BCl3, BH3, AlCl3, and AlH3 acting as Lewis acids through the B or Al centre with Lewis base units: NCH, N2, NH3, and Cl− anion. These complexes are linked by triel bonds: B/Al⋅⋅⋅N or B/Al⋅⋅⋅Cl. The Quantum Theory of ´Atoms in Molecules´ approach, Natural Bond Orbital method, and the decomposition of energy of interaction were applied to characterise the latter links. The majority of complexes are connected through strong interactions possessing features of covalent bonds and characterised by short intermolecular distances, often below 2 Å. The BCl3⋅⋅⋅N2 complex is linked by a weak interaction corresponding to the B⋅⋅⋅N distance of ~3 Å. For the BCl3⋅⋅⋅NCH complex, two configurations corresponding to local energetic minima are observed, one characterised by a short B⋅⋅⋅N distance and a strong interaction and another one characterised by a longer B⋅⋅⋅N distance and a weak triel bond. The tetrahedral triel structure is observed for complexes linked by strong triel bonds, while, for complexes connected by weak interactions, the structure is close to the trigonal pyramid, particularly observed for the BCl3⋅⋅⋅N2 complex.

scholarly journals Recent Synthesis Developments of Organoboron Compounds via Metal-Free Catalytic Borylation of Alkynes and Alkenes

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 101 ◽  
Author(s):  
Yanmei Wen ◽  
Chunmei Deng ◽  
Jianying Xie ◽  
Xinhuang Kang
Keyword(s):  
Lewis Acids ◽  
Heterocyclic Carbenes ◽  
Lewis Base ◽  
Organoboron Compounds ◽  
Lewis Bases ◽  
Metal Free ◽  
Recent Synthesis

Diboron reagents have been traditionally regarded as “Lewis acids”, which can react with simple Lewis base to create a significant nucleophilic character in one of boryl moieties. In particular, bis(pinacolato)diboron (B2pin2) reacts with simple Lewis bases, such as N-heterocyclic carbenes (NHCs), phosphines and alkoxides. This review focuses on the application of trivalent nucleophilic boryl synthon in the selective preparation of organoboron compounds, mainly through metal-free catalytic diboration and the β-boration reactions of alkynes and alkenes.

Halogeno-und Pseudohalogeno-tris(pentahaptocyclopentadienyl)uran(IV)- Komplexe als Lewis-Säuren: Darstellung und Struktur trigonal-bipyramidaler Uran-Organyle des Typs [(η5 -C5H5)3UXL] / Tris(pentahaptocyclopentadienyl)uranium(IV) Halides and Pseudohalides as Lewis-Acids: Preparation and Structure of Uranium Organyls [(η5 -C5H5)3UXL] with Trigonal-Bipyramidal Coordination

1978 ◽  
Vol 33 (12) ◽  
pp. 1393-1397 ◽  
Author(s):  
R. D. Fischer ◽  
E. Klähne ◽  
J. Kopf
Keyword(s):  
Structure Analysis ◽  
Lewis Acids ◽  
Lewis Base ◽  
Lewis Acidity ◽  
X Ray ◽  
Trigonal Bipyramidal Coordination ◽  
Trigonal Bipyramidal ◽  
Linear Alignment ◽  
Specific Reactions

Abstract The first two examples of a novel series of organo-actinide complexes, [Cp3UXL] (Cp = η5 -C5H5, X = halide or pseudohalide anion, L = uncharged Lewis base), are described. The X-ray structure analysis of the system with X = NCS and L = CH3CN confirms an almost linear alignment (H3)CCNUNCS along with the coplanarity of the three Cp ring normals. The remarkable Lewis acidity of certain Cp3UX-compounds appears to be essential for the formation of oligomeric species [Cp3UX]∞ as well as for specific reactions of monomeric CP3UX.

Fluorinated 9-borafluorenes vs. conventional perfluoroaryl boranes — Comparative Lewis acidity

2005 ◽  
Vol 83 (12) ◽  
pp. 2098-2105 ◽  
Author(s):  
Preston A Chase ◽  
Patricio E Romero ◽  
Warren E Piers ◽  
Masood Parvez ◽  
Brian O Patrick
Keyword(s):  
Key Words ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Strength ◽  
Lewis Base ◽  
Lewis Acidity ◽  
Electrochemical Studies ◽  
Steric Factors

Perfluorinated 9-phenyl-9-borafluorene, 1, is an antiaromatic analog of the well-known tris(pentafluorophenyl)borane. Spectroscopic, structural, and electrochemical studies have been performed on 1 and its Lewis base adducts with MeCN, THF, and PMe3 with a view to assessing its comparative Lewis acid strength relative to B(C6F5)3. For the sterically undemanding Lewis base MeCN, 1 and B(C6F5)3 have comparable LA strengths, while for more sterically prominent THF, 1 is clearly the stronger Lewis acid (LA) based on competition experiments. We conclude that steric factors, rather than antiaromaticity, are the most important determinants in the LA strength differences between 1 and B(C6F5)3.Key words: boranes, Lewis acids, fluorinated compounds, heterocycles.

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