Bicyclic Systems with Bridgehead (Ring Junction) Boron Atoms

Bubnov, Yu. N.; Gurskii, M. E.; Erdyakov, Sergey Yu.

doi:10.1016/b978-008044992-0.01113-5

Cited by 4 publications

(5 citation statements)

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“…This is because solid 1-boraadamantane exists as a plastic meso-phase, which shows an isotropic random orientation of the molecules; its meso-phase transforms into organized crystals only below À90 8C. [5] For these reasons, there are so far only reports on structures of several 1-boraadamantane adducts in the crystal phase. [5] These obtained data are of course of rather limited use in the discussion of properties and reactivity on the basis of the geometrical features of free 1-boraadamantane molecules, because the influence of Abstract: Base-free 3-methyl-1-boraadamantane was synthesized by starting from its known THF adduct, transforming it to a butylate-complex with n-butyllithium, cleaving the cage with acetyl chloride to give 3-n-butyl-5methyl-7-methylene-3-borabicyclo-A C H T U N G T R E N N U N G [3.3.1]nonane and closing the cage again by reacting the latter with dicyclohexylborane.…”

Section: Introductionmentioning

confidence: 99%

Structure and Bonding Nature of the Strained Lewis Acid 3‐Methyl‐1‐boraadamantane: A Case Study Employing a New Data‐Analysis Procedure in Gas Electron Diffraction

Vishnevskiy

Abaev

Rykov

et al. 2012

Chemistry A European J

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Base-free 3-methyl-1-boraadamantane was synthesized by starting from its known THF adduct, transforming it to a butylate-complex with n-butyllithium, cleaving the cage with acetyl chloride to give 3-n-butyl-5-methyl-7-methylene-3-borabicyclo[3.3.1]nonane and closing the cage again by reacting the latter with dicyclohexylborane. The identity of 3-methyl-1-boraadamantane was proven by (1) H, (11) B and (13) C NMR spectroscopy and elemental analysis. The experimental equilibrium structure of the free 3-methyl-1-boraadamantane molecules has been determined at 100 °C by using gas-phase electron diffraction. For this structure determination, an improved method for data analysis has been introduced and tested: the structural refinement versus gas-phase electron diffraction data (in terms of Cartesian coordinates) with a set of quantum-chemically derived regularization constraints for the complete structure under optimization of a regularization constant, which maximizes the contribution of experimental data while retaining a stable refinement. The detailed analysis of parameter errors shows that the new approach allows obtaining more reliable results. The most important structural parameters are: r(e) (B-C)(av) =1.556(5) Å, angle(e) (C-B-C)(av) =116.5(2)°. The configuration of the boron atom is pyramidal with ∑ angle (C-B-C)=349.4(4)°. The nature of bonding was analyzed further by applying the natural bond orbital (NBO) and atoms in molecules (AIM) approaches. The experimentally observed shortening of the B-C bonds and elongation of the adjacent C-C bonds can be explained by the σ(C-C)→p(B) hyperconjugation model. Both NBO and AIM analyses predict that the B-C bonds are significantly bent in the direction out of the cage.

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Section: Introductionmentioning

confidence: 99%

Structure and Bonding Nature of the Strained Lewis Acid 3‐Methyl‐1‐boraadamantane: A Case Study Employing a New Data‐Analysis Procedure in Gas Electron Diffraction

Vishnevskiy

Abaev

Rykov

et al. 2012

Chemistry A European J

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“…This transformation was performed to demonstrate possibilities of boron chemistry. Application of 1-boraadamantanes in synthesis was reviewed [7,18].…”

Section: Reactions With Ethyl Orthoformatementioning

confidence: 99%

Allylic boranes are chemist’s best friends: Reactivity, applications, new opportunities

Bubnov

Gurskii

Erdyakov

et al. 2009

Journal of Organometallic Chemistry

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“…The allylboron−acetylene condensation (ABAC)−thermal regio- and stereospecific reaction of triallyl- and trimethallylborane with terminal acetylenes presents an efficient approach to 7-substituted 3-borabicyclo[3.3.1]non-6-enes (3-BBN) and 1-boraadamantane derivatives including optically active forms . Organoboranes of these types were applied as precursors for various compounds, such as cyclohexene derivatives, bicyclic carbo- and heterocycles, , 1-adamantanols, 1-azaadamantanes, 1-borahomoadamantanes, and 1-adamantylboronates, ,, that are difficult to access by classical synthetic methods. Polyhomologation of 1-boraadamantane was used in the synthesis of polymethylene polymers .…”

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“…The general character of ABAC is not limited by the availability of hydrocarbon precursors, and a number of different acetylene derivatives were utilized in this reaction. ,, On the other hand, modification of the allylborane component is quite nontrivial. Classical variants of the condensation make it possible to synthesize only 7-substituted 1,5-H- and 1,5-dimethyl-3-borabicyclo[3.3.1]non-6-enes (when triallyl- or trimethallylborane are used, Scheme ).…”

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“…Isomeric 3-borabicyclo[3.3.1]non-6-enes 2 and 5 were transformed into derivatives of earlier unavailable 3-methyl-1-boraadamantane. Hydroboration−isomerization ring-closure of bicycles 2 and 5 with borane−THF afforded THF-3-methyl-1-boraadamantane, isolated as a colorless liquid by vacuum distillation (66−69 °C, 2 mmHg). The structure of the resulting 1-boraadamantane does not depend on the double-bond location in starting bicycles 2 and 5 .…”

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Design of Bicyclic and Cage Boron Compounds Based on Allylboration of Acetylenes with Allyldichloroboranes

et al. 2009

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Allylboration of acetylenes with allyldichloroboranes has been proposed as a first step of allylboron-acetylene condensation and a way to design condensation products from stage to stage. The chemistry has been applied to the synthesis of isomeric 3-borabicyclo[3.3.1]non-6enes transformed into 3-methyl-1-boraadamantane and [5-D]-3-methyl-1-boraadamantane derivatives.The allylboron-acetylene condensation (ABAC)-thermal regio-and stereospecific reaction of triallyl-and trimethallylborane with terminal acetylenes presents an efficient approach to 7-substituted 3-borabicyclo[3.3.1]non-6-enes (3-BBN) and 1-boraadamantane derivatives 1 including optically active forms. 2 Organoboranes of these types were applied as precursors for various compounds, such as cyclohexene derivatives, bicyclic carbo-and heterocycles, 1,3 1-adaman-tanols, 1 1-azaadamantanes, 4 1-borahomoadamantanes, 5 and 1-adamantylboronates, 1,2b,6 that are difficult to access by classical synthetic methods. Polyhomologation of 1-boraadamantane was used in the synthesis of polymethylene poly- † N.D. Zelinsky Institute. ‡ A.N. Nesmeyanov Institute.

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Bicyclic Systems with Bridgehead (Ring Junction) Boron Atoms

Cited by 4 publications

References 89 publications

Structure and Bonding Nature of the Strained Lewis Acid 3‐Methyl‐1‐boraadamantane: A Case Study Employing a New Data‐Analysis Procedure in Gas Electron Diffraction

Structure and Bonding Nature of the Strained Lewis Acid 3‐Methyl‐1‐boraadamantane: A Case Study Employing a New Data‐Analysis Procedure in Gas Electron Diffraction

Allylic boranes are chemist’s best friends: Reactivity, applications, new opportunities

Design of Bicyclic and Cage Boron Compounds Based on Allylboration of Acetylenes with Allyldichloroboranes

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