Cationic Boron Complexes

Shitov, O. P.; Ioffe, Sema L.; Тартаковский, В. А.; Новиков, С. С.

doi:10.1070/rc1970v039n11abeh002051

Cited by 28 publications

(15 citation statements)

References 6 publications

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“…The chemistry of the heavier boron‐group‐element cations (Al, Ga, In, and Tl) has been recently reviewed 2. However, low‐coordinate cationic boron compounds have not been thoroughly examined since 1985,3 and their four‐coordinate analogues since 19754, 5 despite the attention being paid to main‐group Lewis acid catalysts and an ever‐increasing search for the limit at which Lewis acidity is maximized without there being a decrease in synthetic utility 6…”

Section: Introductionmentioning

confidence: 91%

“…In the case of boronium ions III , stabilization of the four‐coordinate cations becomes increasingly dominated by steric factors because of the small size of boron 4. With two neutral σ‐donor species (e.g.…”

Section: Syntheses and Structures Of Borocationsmentioning

confidence: 99%

“…In almost all cases, boronium cations consist of two covalently bound ligands and two σ‐donating ligands that serve to partially occupy the unfilled orbitals on boron and thus facilitate a depression of the ground‐state energy of these species. This area has been thoroughly reviewed4, 5 and, owing to the volume of reports of these species and their more common nature, only a selection of recent synthetic results are highlighted herein.…”

Section: Syntheses and Structures Of Borocationsmentioning

confidence: 99%

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Borinium, Borenium, and Boronium Ions: Synthesis, Reactivity, and Applications

2005

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Boron cations are elusive and highly electrophilic species that play a key role in the chemistry of boron. Despite early interest in the chemistry of boron cations, until recently they have largely remained chemical curiosities. However, hints at harnessing their potential as potent electrophiles have begun to appear and developments in weakly coordinating anion technology suggest that this is an area of research that is ripe for exploration. It has been nearly 20 years since the last major review on boron cations; herein we summarize the progress in the area since that time.

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Section: Introductionmentioning

confidence: 91%

Section: Syntheses and Structures Of Borocationsmentioning

confidence: 99%

Section: Syntheses and Structures Of Borocationsmentioning

confidence: 99%

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Borinium, Borenium, and Boronium Ions: Synthesis, Reactivity, and Applications

2005

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“…1 Nöth has used the shorter descriptor “nucleophilic addition” for the same method, but we prefer the longer label because the process involves two stages, (1) reversible formation of a tetracoordinate boron intermediate, and (2) partial or total dissociation to release the borenium salt. Well-established examples of this approach involving amine-stabilized borenium ions were already discussed in connection with Scheme 1.…”

Section: Recent Developments In the Generation Of Observable Borenmentioning

confidence: 99%

“…Older reviews have appeared that address early studies involving a variety of boron cations, 1 or that emphasize the structural, bonding, and theoretical aspects of di-, tri-, and tetracoordinate boron cations (borinium, borenium, and boronium, respectively; Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective

2012

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CONTENTS 1. Introduction 4246 2. History of Borenium Ions: Often Considered, Seldom Confirmed 4247 2.1. Suspected Intermediates in B−N Protonation 4247 2.2. Hypothetical Isomers of Cl 3 B•NHMe 2 4247 2.3. The First Observable Borenium Salt 4247 2.4. Nucleophilic Substitution of X 3 B•NR 3 and Py•BF 2 X 4248 2.5. Aminoborenium Ions, Stabilization by n-Delocalization 4249 3. Recent Developments in the Generation of Observable Borenium Intermediates 4249 3.1. Electrophilic Activation by Protonation or by Lewis Acid Catalysis 4249 3.2. Halide Abstraction by a Halophile 4250 3.3. The Borinium−Borenium Interface: Gas-Phase Oxyborenium Ions 4251 3.4. Borenium Salt Generation by Hydride Abstraction 4251 3 . 4 . 1 . H y d r i d e A b s t r a c t i o n b y T r i s -(pentafluorophenyl)borane 4251 3.4.2. Hydride Abstracton by Trityl Salts 4252 3.4.3. Hydride-Bridged Borenium Salt Dimers 4252 3.5. Borenium Ion Generation by Nucleophilic Addition−Heterolysis 4253 4. Borenium Lewis Acidity vs Structure 4254 4.1. Experimental Evaluation of Lewis Acidity 4254 4.2. Computational Evaluation of Borenium Lewis Acidity 4255 5. Borenium Ions and Stereogenic Boron 4257 5.1. Racemization by Heterolysis 4257 5.2. Asymmetric Memory at Stereogenic Boron 4257 5.3. Chiral Salicylaldimine Boronate Complexes 4258 6. Enantioselective Catalysis and Chiral Borenium Ions 4259 6.1. The Dual Function of Oxazaborolidines in the CBS Reduction 4260 6.2. The Role of Borenium Species in Diels−Alder Catalysis 4261 6.3. Reactivity and Scope of Oxazaborolidine-Derived Diels−Alder Catalysts 4263 6.4. Miscellaneous Uses of Chiral Borenium Lewis Acid Catalysts 4265 7. Miscellaneous Applications of Borenium Lewis Acids 4266 7.1. B−O Activation 4266 7.2. Lewis Acidity and π-Conjugated Borenium Analogues 4267 7.3. π-Conjugated Borenium Analogues as Selective Anion Sensors 4268 7.4. Tricoordinate Boron in Structures Containing Metal Cations 4269 8. Borenium Reagents for C−B Bond Formation 4269 8.1. Borenium Ion Equivalents 4269 8.2. Do Borenium Ions Participate in Hydroboration Chemistry? 4270 8.3. Borenium Equivalents in Electrophilic Aromatic Borylation 4271 8.3.1. Intramolecular Borylation 4271 8.3.2. Intermolecular Borylation 4272 8.3.3. Recent Developments in Muetterties Borylation (BX3 plus Proton Scavenger) 4275 9. Extension of Borenium Chemistry to Neighboring Fields and Unusual Environments 4276 9.1. N-Heterocyclic Carbenes as Stabilizing Ligands for Borenium Salts 4276 9.2. Miscellaneous Related Topics Involving BH Species 4277 10. Summary 4278 Author Information 4279 Corresponding Author 4279 Notes 4279 Biographies 4279 Acknowledgments 4279 References 4279

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