Cyclodisilazane in cis-Konformation -eine einfache Synthese / Cyclodisilazanes in cis Conformation -a Facile Synthesis

Klingebiel, Uwe; Tecklenburg, B.; Noltemeyer, Mathias; Schmidt‐Bäse, Dieter; Herbst‐Irmer, Regine

doi:10.1515/znb-1998-0314

Cited by 10 publications

(8 citation statements)

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“…42 A second-order dependence on LiCl suggested a complex gegenion, maybe a cationic triple ion. 43 The bridging THF in computationally viable 28 is a motif that we find highly appealing as central to the final aggregate scission.…”

Section: Case Studiesmentioning

confidence: 88%

Lithium Diisopropylamide: Nonequilibrium Kinetics and Lessons Learned about Rate Limitation

et al. 2017

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The kinetics of lithium diisopropylamide (LDA) in tetrahydrofuran under non-equilibrium conditions are reviewed. These conditions correspond to a class of substrates in which the rates of LDA aggregation and solvation events are comparable to the rates at which various fleeting intermediates react with substrate. Substrates displaying these reactivities, by coincidence, happen to be those that react at tractable rates on laboratory timescales at −78 °C. In this strange region of non-limiting behavior, rate-limiting steps are often poorly defined, sometimes involve deaggregation and at other times include reaction with substrate. Changes in conditions routinely cause shifts in the rate-limiting steps, and autocatalysis is prevalent and can be acute. The studies are described in three distinct portions: (1) methods and strategies used to deconvolute complex reaction pathways, (2) the resulting conclusions about organolithium reaction mechanisms, and (3) perspectives on the concept of rate limitation reinforced by studies of LDA in tetrahydrofuran at −78 °C under non-equilibrium conditions.

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Section: Case Studiesmentioning

confidence: 88%

Lithium Diisopropylamide: Nonequilibrium Kinetics and Lessons Learned about Rate Limitation

et al. 2017

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“…Adduct 30 is structurally similar to a halide adduct tentatively assigned spectroscopically. 50 Moreover, the Li–Cl–Li cationic triple ion fragment is well precedented 51 and is computationally preferred relative to the simple lithium counterion. 52 (The heptasolvation of the (THF) 3 Li–Cl–Li(THF) 4 counterion is odd, but it is the preferred form computationally.)…”

Section: Discussionmentioning

confidence: 99%

Regioselective Lithium Diisopropylamide-Mediated Ortholithiation of 1-Chloro-3-(trifluoromethyl)benzene: Role of Autocatalysis, Lithium Chloride Catalysis, and Reversibility

Hoepker

Gupta

et al. 2011

J. Am. Chem. Soc.

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Ortholithiation of 1-chloro-3-(trifluoromethyl)benzene with lithium diisopropylamide (LDA) in tetrahydrofuran at −78 °C displays characteristics of reactions in which aggregation events are rate limiting. Metalation with lithium chloride-free LDA involves a rate-limiting deaggregation via dimer-based transition structures. The post-rate-limiting proton transfers are suggested to involve highly solvated triple ions. Autocatalysis by the resulting aryllithiums or catalysis by traces (<100 ppm) of LiCl divert the reaction through di- and trisolvated monomer-based pathways for metalation at the two and six positions, respectively. The regiochemistry is dictated by a combination of kinetically controlled metalations overlayed by an equilibration involving diisopropylamine that is shown to occur by the microscopic reverse of the monomer-based metalations.

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“…161.0(8) 162.3 (7) 200.0 (2) 164.3 (7) 111.5(7) 96.2(5) 102.1(5) 141.8(6) 96.9(4) 103.0(4) 102.2(5) ( 1 )-0(80) 107.2(2) Symmetrietransformationen für die äquivalenten Atome:…”

Section: Ergebnisse Undunclassified

“…Eine Suspension von 0.01 mol des jeweiligen lithiierten Amins in 100 ml «-Hexan Di-amino-2,4,6-tri-tert-butylphenylfluorsilane (6,7) 0.1 mol 1 in 100 ml n-Hexan/THF werden beim R.T. mit 0.2 mol des lithiierten Amins, ebenfalls in 100 ml »-Hexan/THF versetzt und 1 h zum Sieden erhitzt. Der Reaktionsfortschritt wird l9F-NMR-spektroskopisch ver folgt.…”

Section: Amino-246-tri-tert-butylphenyl-difluorsilane (2 -4)unclassified

“…Lithiumamide kri stallisieren als vier-, sechs-und achtgliedrige Rin ge, in Ringstapeln und Leiterstrukturen [4,5]. Wir nutzen lithiierte Aminohalogensilane zur Synthe se von Iminosilanen [6] und Silaamididen [7], Zur Aufklärung der Bildungsmechanismen dieser Ver bindungen untersuchten wir Kristallstrukturen der Lithiumderivate und fanden, daß sowohl die Aminosubstituenten als auch die verwendeten Lösungs mittel einen maßgeblichen Einfluß auf die Struk * Sonderdruckanforderungen an Prof. Dr. U. Klingebiel. turen und somit die Reaktivität dieser Lithiumver bindungen haben.…”

Section: Introductionunclassified

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2.4.6-Tri-tert-butylphenylaminofluorsilane und Lithium-bis(2,4,6-tri tert- butylphenyldifluorsilyl)amid - im Kristall ein Polymer / 2.4.6-Tri-tert-butylphenylaminofluorosilanes and Lithium-bis(2,4,6-tri-tert-butylphenyldifluorosilyl) amide - in the Crystal a Polymer

Herbst‐Irmer¹,

Klingebiel

Noltemeyer

1999

Zeitschrift Für Naturforschung B

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2,4,6-Tri-tert-butylphenyltrifluorosilane (1) reacts with lithium amides to give the aminofluorosilanes (2 - 7); RSiF2NHR′ (R = 2,4,6-Me3CC6H2; R′ = H (2), CMe3 (3), SiMe2CMe3 (4)), (R-SiF2)2NH (5), RSiF(NHR′)2. R′ = CMe3 (6), C6H5 (7). The reaction of 5 with BuLi in THF leads to the formation of the monomeric lithium derivative 8, R-SiF2Li⊕(THF)3-N⊖ -SiF2R. The polymeric lithium derivative 9 [R-SiF2-N⊖-SiRF2Li⊕(THF)2]n is obtained by recrystallisation of 8 in THF. In 8 and 9 lithium is only coordinated to fluorine and THF. Hydrolysis of 8 or 9 lead to the 1,3-disiloxane 10, (RSiF2)2O . 10 shows linearity at the oxygen and short Si-O bond lengths.

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Cyclodisilazane in cis-Konformation -eine einfache Synthese / Cyclodisilazanes in cis Conformation -a Facile Synthesis

Cited by 10 publications

References 0 publications

Lithium Diisopropylamide: Nonequilibrium Kinetics and Lessons Learned about Rate Limitation

Lithium Diisopropylamide: Nonequilibrium Kinetics and Lessons Learned about Rate Limitation

Regioselective Lithium Diisopropylamide-Mediated Ortholithiation of 1-Chloro-3-(trifluoromethyl)benzene: Role of Autocatalysis, Lithium Chloride Catalysis, and Reversibility

2.4.6-Tri-tert-butylphenylaminofluorsilane und Lithium-bis(2,4,6-tri tert- butylphenyldifluorsilyl)amid - im Kristall ein Polymer / 2.4.6-Tri-tert-butylphenylaminofluorosilanes and Lithium-bis(2,4,6-tri-tert-butylphenyldifluorosilyl) amide - in the Crystal a Polymer

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