Carbonylation of Lithium Dialkylamides to Give Carbamoyllithiums

Rautenstrauch, Valentin; Joyeux, M.

doi:10.1002/anie.197900832

Cited by 31 publications

(9 citation statements)

References 11 publications

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“…The reactivity of lithium alkyls and amides with carbon monoxide has been a subject of study for over a century, albeit the electrophilic trapping of the resultant acyl or carbamoyl anion equivalents has only been achieved infrequently. − Related chemistry induced by organo- or amidomagnesium derivatives has received even less attention, despite the possibility that the reduced nucleophilicity of the resultant species may provide greater selectivity in subsequent transformations . Prompted by this lacuna, we have recently reported that the reaction of the β-diketiminato magnesium hydride [HC{(Me)CNDipp} 2 MgH] 2 ( 4 , Dipp = 2,6-di-isopropylphenyl) with 1 atm of CO results in the production of the cis -ethenediolate species ( 5 ) .…”

Section: Introductionmentioning

confidence: 99%

Alkaline Earth-Centered CO Homologation, Reduction, and Amine Carbonylation

et al. 2017

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Reactions of β-diketiminato magnesium and calcium hydrides with 1 atm of CO result in a reductive coupling process to produce the corresponding derivatives of the cis-ethenediolate dianion. Computational (DFT) analysis of this process mediated by Ca, Sr, and Ba highlights a common mechanism and a facility for the reaction that is enhanced by increasing alkaline earth atomic weight. Reaction of CO with PhSiH in the presence of the magnesium or calcium hydrides results in catalytic reduction to methylsilane and methylene silyl ether products, respectively. These reactions are proposed to ensue via the interception of initially formed group 2 formyl intermediates, an inference which is confirmed by a DFT analysis of the magnesium-centered reaction. The computational results identify the rate-determining process, requiring traversal of a 33.9 kcal mol barrier, as a Mg-H/C-O σ-bond metathesis reaction, associated with the ultimate cleavage of the C-O bond. The carbonylation reactivity is extended to a variety of magnesium and calcium amides. With primary amido complexes, which for calcium include a derivative of the parent [NH] anion, CO insertion is facile and ensues with subsequent nitrogen-to-carbon migration of hydrogen to yield a variety of dinuclear and, in one case, trinuclear formamidate species. The generation of initial carbenic carbamoyl intermediates is strongly implicated through the isolation of the CO insertion product of a magnesium N-methylanilide derivative. These observations are reinforced by a DFT analysis of the calcium-centered reaction with aniline, which confirms the exothermicity of the formamidate formation (ΔH = -67.7 kcal mol). Stoichiometric reduction of the resultant magnesium and calcium formamidates with pinacolborane results in the synthesis of the corresponding N-borylated methylamines. This takes place via a sequence of reactions initiated through the generation of amidatohydridoborate intermediates and a cascade of reactivity that is analogous to that previously reported for the deoxygenative hydroboration of organic isocyanates catalyzed by the same magnesium hydride precatalyst. Although a sequence of amine formylation and deoxygenation may be readily envisaged for the catalytic utilization of CO as a C source in the production of methylamines, our observations demonstrate that competitive amine-borane dehydrocoupling is too facile under the conditions of 1 atm of CO employed.

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Section: Introductionmentioning

confidence: 99%

Alkaline Earth-Centered CO Homologation, Reduction, and Amine Carbonylation

et al. 2017

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“…In addition, related group 1 phosphides react with CO via transient carbene-type intermediates, suggesting an analogy to species commonly proposed as FT intermediates. While studies in the 1970s and 1980s had probed reactions of lithium amides with CO for organic synthesis, − no study has exploited such accessible systems for reactions with CO/H 2 mixtures. Herein, we show that Cy 2 NLi (Cy = cyclohexyl) effects the concurrent fundamental steps of FT chemistry, namely C–C and C–H bond formation, under remarkable mild conditions.…”

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confidence: 99%

Lithium Dicyclohexylamide in Transition-Metal-Free Fischer–Tropsch Chemistry

Grimme

et al. 2021

J. Am. Chem. Soc.

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Lithium dicyclohexylamide (Cy 2 NLi) reacts with syn-gas or CO to generate transient intermediates with carbene character, which are capable of reacting further with CO or H 2 , effecting sequential C−C and C−H bond formations from CO or H 2 , thus providing a transition-metal-free avenue to the fundamental reactions of the Fischer−Tropsch process. Further experimental and computational data indicate that reactions with CO and H 2 are thermodynamically accessible, with a kinetic bias toward CO homologation.

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“…Most progress has been made with rhodium catalysts, but platinum-catalyzed reactions have also shown promise. Hydroformylation of styrene, for example, using PtCI2/SnCI2 in the presence of the chiral ligand (-)-BPPM (4) and triethyl orthoformate gives the enantiomerically pure acetal of 2-phenylpropanal, together with the acetal of 3-phenylpropanal (equation 8).21 A number of other chelating biphosphines, for example DIOP (4) and CHIRAPHOS, have been used with rhodium and platinum systems but generally optical yields do not exceed 50%.22…”

Section: Substitutive Carbonylationmentioning

confidence: 99%

Carbonylation and Decarbonylation Reactions

Thompson¹

1991

Comprehensive Organic Synthesis

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Carbonylation of Lithium Dialkylamides to Give Carbamoyllithiums

Cited by 31 publications

References 11 publications

Alkaline Earth-Centered CO Homologation, Reduction, and Amine Carbonylation

Alkaline Earth-Centered CO Homologation, Reduction, and Amine Carbonylation

Lithium Dicyclohexylamide in Transition-Metal-Free Fischer–Tropsch Chemistry

Carbonylation and Decarbonylation Reactions

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