Mechanistic study on the reaction of pinB-BMes<sub>2</sub>with alkynes based on experimental investigation and DFT calculations: gradual change of mechanism depending on the substituent

Wu, Linlin; Kojima, Chiemi; Lee, Ka‐Ho; Morisako, Shogo; Lin, Zhenyang; Yamashita, Makoto

doi:10.1039/d1sc02863d

Cited by 8 publications

(5 citation statements)

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“…This has expanded on the work of Schlesinger using B 2 X 4 (X = halide), 2 and a number of electrophilic diboron(4) compounds now have been reported, including examples that can borylate π nucleophiles and activate small molecules (e.g., H 2 and CO). 3 Parallel to this, there has been significant research into the chemistry of bidentate Lewis acids containing two electrophilic boron centers but no B–B bond, herein termed bis-boranes. While bis-boranes have been widely applied for small-molecule activation [e.g., in frustrated Lewis pairs (FLPs)] 4 and in anion sensing, 5 the use of bis-boranes in the double borylation of π nucleophiles is relatively underexplored ( vide infra ).…”

Section: Introductionmentioning

confidence: 99%

“…Recent years have seen a resurgence in the chemistry of more (relative to B 2 Pin 2 ) electrophilic diboron(4) compounds. This has expanded on the work of Schlesinger using B 2 X 4 (X = halide), and a number of electrophilic diboron(4) compounds now have been reported, including examples that can borylate π nucleophiles and activate small molecules (e.g., H 2 and CO) . Parallel to this, there has been significant research into the chemistry of bidentate Lewis acids containing two electrophilic boron centers but no B–B bond, herein termed bis-boranes.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

et al. 2022

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Dimeric aminoboranes, [H 2 BNR 2 ] 2 (R = Me or CH 2 CH 2 ) containing B 2 N 2 cores, can be activated by I 2 , HNTf 2 (NTf 2 = [N(SO 2 CF 3 ) 2 ]), or [Ph 3 C][B(C 6 F 5 ) 4 ] to form isolable H 2 B(μ-NR 2 ) 2 BHX (for X = I or NTf 2 ). For X = [B(C 6 F 5 ) 4 ] − further reactivity, presumably between [H 2 B(μ-NMe 2 ) 2 BH][B(C 6 F 5 ) 4 ] and aminoborane, forms a B 3 N 3 -based monocation containing a three-center two electron B-(μ-H)-B moiety. The structures of H 2 B(μ-NMe 2 ) 2 BH(I) and [(μ-NMe 2 )BH(NTf 2 )] 2 indicated a sterically crowded environment around boron, and this leads to the less common O-bound mode of NTf 2 binding. While the iodide congener reacted very slowly with alkynes, the NTf 2 analogues were more reactive, with hydroboration of internal alkynes forming (vinyl) 2 BNR 2 species and R 2 NBH(NTf 2 ) as the major products. Further studies indicated that the B 2 N 2 core is maintained during the first hydroboration, and that it is during subsequent steps that B 2 N 2 dissociation occurs. In the mono-boron systems, for example, i Pr 2 NBH(NTf 2 ), NTf 2 is N-bound; thus, they have less steric crowding around boron relative to the B 2 N 2 systems. Notably, the monoboron systems are much less reactive in alkyne hydroboration than the B 2 N 2 -based bis-boranes, despite the former being three coordinate at boron while the latter are four coordinate at boron. Finally, these B 2 N 2 electrophiles are much more prone to dissociate into mono-borane species than pyrazabole [H 2 B(μ-N 2 C 3 H 3 )] 2 analogues, making them less useful for the dir...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

et al. 2022

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“…After these pioneering works, there were many examples of such base-catalyzed diboration of unsaturated compounds. In these reactions, alkali metal alkoxides [ 87 , 88 , 89 ], amines [ 90 , 91 , 92 ], and butyllithium [ 93 , 94 , 95 , 96 ] were used as bases.…”

Section: Boron-centered Interelement Compounds In Radical Addition Re...mentioning

confidence: 99%

Metal-Free One-Pot Multi-Functionalization of Unsaturated Compounds with Interelement Compounds by Radical Process

Yamamoto

2023

Molecules

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In recent years, the importance of “environmentally friendly manufacturing” has been increasing toward the establishment of a resource-recycling society. In organic synthesis, as well, it is becoming increasingly important to develop new synthetic strategies with resource conservation and the recycling of elemental resources in mind, rather than just only synthesis. Many studies on the construction of frameworks of functional molecules using ionic reactions and transition-metal-catalyzed reactions have been reported, but most of them have focused on the formation of carbon–carbon bonds. However, it is essential to introduce appropriate functional groups at appropriate positions in molecules in order for the molecules to express their functions, and furthermore, the highly selective preparation of multiple functional groups is considered important for the creation of new functional molecules. In this review, we focus on radical reactions with high functional group selectivity and overview the recent progress in practical methods for the simultaneous introduction of multiple functional groups and propose future synthetic strategies that emphasize the recycling of elemental resources and environmental friendliness.

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“…In 2014, Yamashita and co-workers prepared an unsymmetrical diborane(4) species 1 from the reaction of B 2 pin 2 and Grignard reagent MesMgBr (Scheme 1). [27][28] Compound 1 exhibited two signals at 34 and 89 ppm in the 11 B NMR spectra. In this unsymmetrical diborane, the polarized BÀ B bond is very reactive toward unsaturated molecules.…”

Section: Sp 2 -Sp 2 Diboron Compoundsmentioning

confidence: 99%

Neutral and Anionic Diboron Compounds Bearing Electron‐Precise B−B Bond

Li,

Xu,

et al. 2023

The Chemical Record

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Electron‐precise B−B bonded compounds are valuable reagents in organic syntheses, which can be used as key starting material for the synthesis of functionalized organoboranes. Bis(pinacolato)diborane(4) B2pin2 and its derivatives are among the most studied diboron species. However, their B−B bonds usually need to be activated by transition metal catalysts or bases for further transformations. Recently, many well‐designed/reactive electron‐precise B−B bonded compounds have been developed, which could facilitate direct reactions with small molecules, unsaturated substrates, and electrophiles. This review highlights the synthesis, structure, and reactivity of neutral and anionic B−B bonded compounds.

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Mechanistic study on the reaction of pinB-BMes₂with alkynes based on experimental investigation and DFT calculations: gradual change of mechanism depending on the substituent

Abstract: Transition-metal free direct and base-catalyzed 1,2-diborations of arylacetylenes using pinB-BMes2 provided syn/anti-isomeric mixture of diborylalkenes. The kinetic analysis showed that the reaction rate and isomer ratio were affected by reaction...

Cited by 8 publications

References 48 publications

Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

Metal-Free One-Pot Multi-Functionalization of Unsaturated Compounds with Interelement Compounds by Radical Process

Neutral and Anionic Diboron Compounds Bearing Electron‐Precise B−B Bond

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Mechanistic study on the reaction of pinB-BMes2with alkynes based on experimental investigation and DFT calculations: gradual change of mechanism depending on the substituent

Abstract: Transition-metal free direct and base-catalyzed 1,2-diborations of arylacetylenes using pinB-BMes2 provided syn/anti-isomeric mixture of diborylalkenes. The kinetic analysis showed that the reaction rate and isomer ratio were affected by reaction...

Cited by 8 publications

References 48 publications

Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

Synthesis of Electrophiles Derived from Dimeric Aminoboranes and Assessing Their Utility in the Borylation of π Nucleophiles

Metal-Free One-Pot Multi-Functionalization of Unsaturated Compounds with Interelement Compounds by Radical Process

Neutral and Anionic Diboron Compounds Bearing Electron‐Precise B−B Bond

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Mechanistic study on the reaction of pinB-BMes₂with alkynes based on experimental investigation and DFT calculations: gradual change of mechanism depending on the substituent