Carbonylation of Lithium Monoalkylamides to Give <i>N</i>‐Lithio(alkyl)formamides

Rautenstrauch, Valentin; Joyeux, M.

doi:10.1002/anie.197900851

Cited by 23 publications

(7 citation statements)

References 6 publications

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“…Because CO is a poor electrophile, we have also considered a second mechanism for CO insertion, illustrated in Scheme , path A. This mechanism is initiated by dissociation of one arm of a dmpe ligand from the iron center in 2 and coordination of CO. Migratory insertion of CO into the M−N bond would yield the intermediate trans -(dmpe) 2 Fe(H)(C(O)NH 2 ) ( 7 ). ,, A similar mechanism is observed with lithium amide and lithium alkyl species, which are carbonylated by CO through a nucleophilic mechanism . β-Hydride elimination of isocyanic acid, followed by insertion into the iron−hydride bond, would give rise to complex 6 .…”

Section: Resultsmentioning

confidence: 85%

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Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

and

Bergman

2004

Organometallics

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The iron amido complex (dmpe) 2 Fe(H)(NH 2 ) (2; dmpe ) 1,2-bis(dimethylphosphino)ethane) has been prepared from the hydrido chloride complex using sodium amide in a liquid ammonia/THF solvent mixture. The complex is a mixture of trans and cis isomers in solution, although it crystallizes as the trans isomer exclusively. Complex 2 is a strong base, although somewhat weaker than the ruthenium amido complex trans-(dmpe) 2 Ru(H)(NH 2 ) (1). Amido complex 2 deprotonates several weak acids, and some of these deprotonations result in displacement of ammonia, while others do not. The basicity of complex 2 is further demonstrated with systems in which acidic substrates are reversibly deprotonated. Complex 2 undergoes H/D exchange with toluene-d 8 , and it catalyzes H/D exchange between toluened 8 and several other extremely weak acids. An investigation into the mechanism of the H/D exchange and isomerization reactions of trans-9,10-diisopropyl-9,10-dihydroanthracene (trans-4) using 1, 2, and cis-(PMe 3 ) 4 Ru(H)(NH 2 ) (5) as catalysts demonstrates that the H/D exchange reactions proceed through formation of ion pairs, although it is surprising that displacement of ammonia is never observed. Amido complexes 1 and 2, as well as the hydroxo complex trans-(dmpe) 2 Ru(H)(OH), are also good nucleophiles. For example, they ring-open 1,3-di-tert-butylaziridinone in a nucleophilic manner to form trans-(dmpe) 2 M(H)(XC(O)CH-(t-Bu)NH(t-Bu)) (M ) Fe, X ) NH; M ) Ru, X ) NH, O). A second example is an unusual insertion of carbon monoxide into the N-H bond of 2 to form the carboxamide complex trans-(dmpe) 2 Fe(H)(NHCHO) (6). Although CO is a poor electrophile, mechanistic experiments suggest that this reaction proceeds through direct attack of the amide nitrogen on the CO carbon.

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Section: Resultsmentioning

confidence: 85%

“…Three possible mechanisms have been considered to explain the unusual CO insertion. The first involves direct attack of the amide nitrogen on the carbon of free CO to form a zwitterionic intermediate that gives the observed product ( 6 ) after proton transfer (Scheme ) , path A.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

and

Bergman

2004

Organometallics

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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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“…One reason for that may arise from the difficulty of insertion of CO into an early-metal-amide bond, 3 whereas such insertion is a known reaction for late-transition-metal complexes 4 and, to a lesser extent, for some actinide compounds. 5,6 It is worth noting that alkali-metal salts of strongly basic nitrogen are known to attack CO. 7,8 As there is still a need for new catalysts, in particular those that could operate under milder conditions, we have embarked on the study of bimetallic systems combining an early transition metal (that could form M-NR bonds) with a carbonyl complex (that could effect the carbonylation). Herein we report our first results concerning the synthesis and structure of Ti/Mo heterobimetallic systems that led us to characterize the first "Mo/η 6 -arene-imido/Ti" complex as well as "Mo/aminocarbene/Ti" complexes.…”

Section: Introductionmentioning

confidence: 99%

“…With the exception of tungsten, studies of early-transition-metal-catalyzed carbonylation of amines are unknown. One reason for that may arise from the difficulty of insertion of CO into an early-metal−amide bond, whereas such insertion is a known reaction for late-transition-metal complexes and, to a lesser extent, for some actinide compounds. , It is worth noting that alkali-metal salts of strongly basic nitrogen are known to attack CO. , …”

Section: Introductionmentioning

confidence: 99%

Imido−Titanium/Molybdenum Heterobimetallic Systems. Switching from η⁶-Arene to Fischer-Type Aminocarbene Complexes by Tuning Reactivity Conditions

Lorber¹,

Vendier²

2010

Organometallics

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Two types of bimetallic titanium/molybdenum systems are described: the first possesses unprecedented η6-arene-imido groups, while the second has Fischer-type aminocarbene ligands bridging the two metals. The (η6-arene)−Mo imido−Ti complex Ti[N(η6-Ar)Mo(CO)3]Cl2(NHMe2)2 (2; Ar = 2,6- i Pr2-C6H3) has been prepared through the reaction of (η6-ArNH2)Mo(CO)3 (3) and TiCl2(NMe2)2. The alternative route from 2 and Ti(NMe2)4/Me3SiCl also afforded 1, but it was contaminated with a small amount of Ti(NAr)Cl2(NHMe2)2 (1). The reaction between the dimeric complexes {Ti(μ-NAr)(NMe2)2}2 and Mo(CO)6 gave complex mixtures of products, among which the Fischer-type aminocarbene complex [(CO)5Mo{C(NMeCH2NMe2)O}Ti(N-2,6-Pr i 2-C6H3)(NMe2)(NHMe2)] (4) could be characterized. The formation of 4 resulted from the nucleophilic attack of the amido −NMe2 to the carbonyl that afforded the titanoxy aminocarbene linker between the Mo and the Ti centers, followed by a subsequent C−H activation of a methyl group of the aminocarbene and C,N coupling with an amido ligand on titanium. Treatment of Ti(NMe2)4 with 1 equiv of Mo(CO)6 produced the titanoxy aminocarbene [(CO)5Mo{C(NMe2)O}Ti(NMe2)3] (5), while in the presence of 1 equiv of ArNH2 the imido complex [(CO)5Mo{C(NMe2)O}Ti(N-2,6-Pr i 2-C6H3)(NMe2)(NHMe2)2] (6) is formed. The molecular structures of 1−6 have been determined by X-ray diffraction.

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Carbonylation of Lithium Monoalkylamides to Give N‐Lithio(alkyl)formamides

Cited by 23 publications

References 6 publications

Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

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

Imido−Titanium/Molybdenum Heterobimetallic Systems. Switching from η⁶-Arene to Fischer-Type Aminocarbene Complexes by Tuning Reactivity Conditions

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Carbonylation of Lithium Monoalkylamides to Give N‐Lithio(alkyl)formamides

Cited by 23 publications

References 6 publications

Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

Synthesis of an Iron Parent Amido Complex and a Comparison of Its Reactivity with the Ruthenium Analog

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

Imido−Titanium/Molybdenum Heterobimetallic Systems. Switching from η6-Arene to Fischer-Type Aminocarbene Complexes by Tuning Reactivity Conditions

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Product

Resources

About

Imido−Titanium/Molybdenum Heterobimetallic Systems. Switching from η⁶-Arene to Fischer-Type Aminocarbene Complexes by Tuning Reactivity Conditions