Lithium <i>tert</i>‐Butyl[phenyl(2,2,6,6‐tetramethylpiperidino)boryl]amide: A Versatile Reagent

Braun, Ulrike; Habereder, Tassilo; Nöth, Heinrich

doi:10.1002/ejic.200400161

Cited by 21 publications

(3 citation statements)

References 46 publications

(29 reference statements)

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“…These intramolecular LP(N) → σ*(As−Cl) donor−acceptor interactions (hyperconjugation, 15.2 and 2.5 kcal/mol in case of species 3 ) account for the rather short As−N distance by introducing a small amount of π interaction (Figure S1, Supporting Information). Similar structural features with short As−N distances have already been observed in a series of aminoarsanes (R 2 N−AsR 1 R 2 ; with R 1 ,R 2 = Cl or Me). ,, …”

Section: Resultssupporting

confidence: 73%

Lewis-Acid-Assisted Methyl Exchange Reactions In Silylated Aminodichloroarsanes

2008

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Lewis-acid-assisted methyl/chlorine, methyl/azide, and methyl/triflate exchange reactions between silicon and arsenic centers have been studied and applied to different silylated aminoarsane species leading to a number of new methylarsane compounds: bis(trimethylsilyl)amino(dichloro)arsane (3) was reacted with GaCl(3) yielding a bis(chlorodimethylsilyl)-tetramethyl-cyclo-disilazane (4) accompanied by the release of Me(2)AsCl, while trimethylsilyl(m-terphenyl)amino(dichloro)arsane (5) (m-terphenyl = 2,6-Mes(2)-C(6)H(3), Mes = 2,4,6-Me(3)C(6)H(2)) reacted with GaCl(3) to give dichloromethylsilyl(m-terphenyl)aminodimethylarsane (6). In the presence of trimethylsilylazide, trimethylsilyl(m-terphenyl)amino(dichloro)arsane displays a methyl/azide exchange triggered by the action of GaCl(3) yielding azidodimethylsilyl(m-terphenyl)amino(chloro)methylarsane (7). Moreover, methyl/triflate exchange reactions have been observed in the reaction of trimethylsilyl(m-terphenyl)amino(dichloro)arsane (i) with 1 equiv of AgOTf (OTf = triflate) yielding N-(trifluoromethylsulfonatodimethylsilyl)-N-(m-terphenyl)amino(methyl)chloroarsane (8) and (ii) with 2 equiv of AgOTf yielding N-(trifluoromethylsulfonatodimethylsilyl)-N-(m-terphenyl)trifluoromethylsulfonatomethylarsane (9). All new compounds (3-9) have been fully characterized by means of vibrational spectroscopy, X-ray, CHN analysis, MS, and NMR studies. A possible reaction mechanism is discussed starting from an initial chloride abstraction and the intermediate formation of a cationic iminoarsane species. In a second step, a methyl shift from the silicon to the arsenic center occurs.

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Section: Resultssupporting

confidence: 73%

Lewis-Acid-Assisted Methyl Exchange Reactions In Silylated Aminodichloroarsanes

2008

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“…The structure of 2 can be described as a ion-contacted aggregate of two oppositely disposed [Li(TMEDA)] + cations coordinated to the tetrahedral anion Zn(OR) 4 2− giving rise to a trimetallic Li···Zn···Li chain arrangement in which the metals are connected through enolate ligands. Compound 3 adopts the same structural motif with the lithium centers solvated by a molecule of the secondary amine TMP(H) instead of being chelated by TMEDA ligands as in 2 . Unfortunately due to a large amount of motion within the TMP(H) ligands, the structure is disordered, which prevents further discussion of the bond lengths and bond angles.…”

Section: Resultsmentioning

confidence: 99%

Metalation of 2,4,6-Trimethylacetophenone Using Organozinc Reagents: The Role of the Base in Determining Composition and Structure of the Developing Enolate

et al. 2008

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The new mixed lithium-zinc enolate compounds [(TMEDA) 2 Li 2 Zn{OC(dCH 2 )Mes} 4 ] (2) and [{TMP(H)} 2 Li 2 Zn{OC(dCH 2 )Mes} 4 ] (3) were prepared by reaction of the sterically demanding ketone 2,4,6-trimethylacetophenone (1) with the all-amido homoleptic zincate [LiZn(TMP) 3 ] (TMP ) 2,2,6,6tetramethylpiperidide). X-ray crystallographic studies revealed that these compounds adopt a trinuclear Li • • • Zn • • • Li chain arrangement with enolate O bridges. In contrast, the metalation of 1 with heteroleptic [(TMEDA)LiZn(TMP)Me 2 ] afforded the dimeric lithium enolate [(TMEDA) 2 Li 2 {OC(dCH 2 )Mes} 2 ] (4) as a crystalline solid, which has been characterized in the solid state by X-ray crystallography, and Me 2 Zn • TMEDA and TMP(H) as coproducts, showing that the dimethylamido zincate behaves as an amide base. The homoleptic zinc enolate [(TMEDA)Zn{OC(dCH 2 )Mes} 2 ] (5) was obtained by reaction of 1 with the zinc amide Zn(TMP) 2 , and its structure was determined by X-ray crystallography. 5 adopts a rarely observed monomeric arrangement where the two enolate groups bind terminally to the zinc. New enolates 2-5 have also been characterized by 1 H, 13 C, and 7 Li NMR spectroscopy in C 6 D 6 solution. DFT studies of the metalation of 1 by Zn(TMP) 2 and Et 2 Zn revealed that the former amide has a much greater kinetic basicity than the latter alkyl reagent.

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“…Interestingly, in the absence of THF the nonvolatile, bulky amine TMP(H), liberated as a coproduct from the deprotonation reaction due to amine basicity, acts as a Lewis donor, capping the lithium and preventing the bimetallic units from linking up further into a ring, as seen in the sodium magnesiate inverse crown in Figure . Dative TMP(H)···Li contacts are relatively rare in the literature, with the bond length in complex 6 [mean, 2.229 Å] being longer than those previously reported in TMP(H)·LiN( t Bu)B(Ph)(TMP) [2.155(5)Å], TMP(H)·Li(μ- i Bu)(μ-TMP)Al i Bu 2 [2.165(5) Å], or [TMP(H)·LiI] 4 [mean, 2.104 Å]…”

Section: Resultsmentioning

confidence: 99%

Structurally Defined Zincated and Aluminated Complexes of Ferrocene Made by Alkali-Metal Synergistic Syntheses

et al. 2015

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This version is available at https://strathprints.strath.ac.uk/51790/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the -6 have also been studied by solution NMR spectroscopic studies.

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Lithium tert‐Butyl[phenyl(2,2,6,6‐tetramethylpiperidino)boryl]amide: A Versatile Reagent

Cited by 21 publications

References 46 publications

Lewis-Acid-Assisted Methyl Exchange Reactions In Silylated Aminodichloroarsanes

Lewis-Acid-Assisted Methyl Exchange Reactions In Silylated Aminodichloroarsanes

Metalation of 2,4,6-Trimethylacetophenone Using Organozinc Reagents: The Role of the Base in Determining Composition and Structure of the Developing Enolate

Structurally Defined Zincated and Aluminated Complexes of Ferrocene Made by Alkali-Metal Synergistic Syntheses

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