Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO<sub>2</sub> for consecutive <i>N</i>-methylation of amines

Maji, Subir; Das, Arpan; Mandal, Swadhin K.

doi:10.1039/d1sc02819g

Cited by 27 publications

(29 citation statements)

References 45 publications

(62 reference statements)

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“…In 2021, Mandal and co‐workers disclosed a highly nucleophilic mesoionic N ‐heterocyclic olefin (mNHO) as a metal‐free catalyst for the synthesis of mono and double N ‐methylated amines using CO 2 as a C1 source and 9‐borabicyclo [3.3.1] nonane (9‐BBN) as hydride donor (Scheme 18). [39] Interestingly, the catalyst is recyclable and sustained over six successive cycles without any alteration in its efficiency.…”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

“…Reaction conditions are optimized using diphenylamine as a model substrate in the presence of 1 atm of CO 2 , a catalytic amount of mNHO, and 0.8 mmol of borane in a Schlenk line (Table 14). Experiments reveal that mNHO works as an efficient catalyst for the N ‐methylation of secondary amines, 9‐BBN is the best hydride source, and THF is the most suitable solvent under mild reaction conditions [39] …”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

“…Remarkably, the authors have extended the scope of protocol to synthesize two commercially available pharmaceuticals such as angustureine (an anti‐malarial drug) and pempidine (a ganglion‐blocking drug), which exhibited the corresponding N ‐methylated product with the yield of 84% and 72%, respectively (Scheme 19). [39] …”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

“…The compound containing‐NH 2 and −NH−Ph group in the same molecule were also successfully methylated (61%) (Scheme 20). [39] …”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

“…In the subsequent step, the formyl group was transferred from the intermediate (3) to N‐borylated amine (4) leading to the formation of formanilide (5) and (9‐BBN) 2 O as a byproduct. The intermediate (5) undergoes reduction and generates intermediate (6), followed by further reduction with mNHO–9‐BBN adduct leads to the formation of final N,N ‐dimethyl aniline along with the formation of (9‐BBN) 2 O as a by‐product [39] …”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

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Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

et al. 2022

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Carbon dioxide (CO 2 ) capture and conversion from renewable resources have recently emerged as a viable alternative to the synthesis of core chemicals. Despite the fact that CO 2 fixation is limited due to its thermodynamic stability and kinetic inertness, researchers are becoming increasingly interested in developing novel routes with the use of CO 2 in synthetic organic chemistry, and the pace of advancements in this field is accelerating. In particular, the development of benign N-and C-methylation reactions employing CO 2 as a C1 synthon instead of conventional methylation reagents would enable the release of lower amounts of waste leading to more sustainable chemical industry. This review presents recent new strategies for the chemical transformation of CO 2 and its incorporation into Nor C-based nucleophiles to provide access to the respective methylamines and methylated (hetero)arenes. Finally, existing limitations in NÀ H, and CÀ H bond activation techniques and future prospects are also discussed. We believe these methodologies will provide a handy reference to the chemists for synthesizing a vast range of methylated molecules in shorter steps by utilizing CO 2 as an advantageous single-carbon source.

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Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

“…The compound containing‐NH 2 and −NH−Ph group in the same molecule were also successfully methylated (61%) (Scheme 20). [39] …”

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

Section: N‐methylation Reactions Using Co2 As a Carbon Sourcementioning

confidence: 99%

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Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

et al. 2022

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C−N Bond Formation Using Paraformaldehyde as C1 Source – Recent Advances

Guo,

Wu,

Wei

2023

Asian J Org Chem

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Recently, polyformaldehyde (PFA) has been used as C1 source to synthesize a series of value‐added compounds due to its low price, stability, low level of toxicity and easy operation. Exploiting paraformaldehyde as C1 source, rather than using traditional methylation reagent to develop benign N‐methylation reactions, can be more environment‐friendly and make the chemical industry more sustainable. In this paper, the chemical transformation of polyformaldehyde and a new strategy of methylating polyformaldehyde with amine compound to methylamine compound are reviewed. These methods will provide a reference for researchers to synthesize a large number of methylamine compounds in a short reaction by using paraformaldehyde as a single carbon source.

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Mesoionische N‐Heterocyclische Olefine verschieben die obere Grenze der Nucleophilie‐Skala

Eitzinger,

Reitz,

Antoni

et al. 2023

Angewandte Chemie

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A series of mesoionic, 1,2,3‐triazole‐derived N‐heterocyclic olefins (mNHOs), which have an extraordinarily electron‐rich exocyclic CC‐double bond, were synthesized and spectroscopically characterized, in selected cases by X‐ray crystallography. The kinetics of their reactions with arylidene malonates, ArCH=C(CO2Et)2, which gave zwitterionic adducts, were investigated photometrically in THF at 20 °C. The resulting second‐order rate constants k2(20 °C) correlate linearly with the reported electrophilicity parameters E of the arylidene malonates (reference electrophiles), thus providing the nucleophile‐specific N and sN parameters of the mNHOs according to the correlation lg k2(20°C) = sN(N + E). With 21 < N < 32, the mNHOs are much stronger nucleophiles than conventional NHOs. Some mNHOs even excel the reactivity of mono‐ and diacceptor‐substituted carbanions. It is exemplarily shown that the reactivity parameters thus obtained allow to calculate the rate constants for mNHO reactions with further Michael acceptors and predict the scope of reactions with other electrophilic reaction partners including carbon dioxide, which gives zwitterionic mNHO‐carboxylates. The nucleophilicity parameters N correlate linearly with a linear combination of the quantum‐chemically calculated methyl cation affinities and buried volumes of mNHOs, which offers a valuable tool to tailor the reactivities of strong carbon nucleophiles.

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Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO₂ for consecutive N-methylation of amines

Abstract: A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2 leading to consecutive double N-methylation of primary amines in presence of 9-borabicyclo[3.3.1]nonane (9-BBN)....

Cited by 27 publications

References 45 publications

Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

C−N Bond Formation Using Paraformaldehyde as C1 Source – Recent Advances

Mesoionische N‐Heterocyclische Olefine verschieben die obere Grenze der Nucleophilie‐Skala

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Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2 for consecutive N-methylation of amines

Abstract: A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2 leading to consecutive double N-methylation of primary amines in presence of 9-borabicyclo[3.3.1]nonane (9-BBN)....

Cited by 27 publications

References 45 publications

Recent Trends in Upgrading of CO2 as a C1 Reactant in N‐ and C‐Methylation Reactions

Recent Trends in Upgrading of CO2 as a C1 Reactant in N‐ and C‐Methylation Reactions

C−N Bond Formation Using Paraformaldehyde as C1 Source – Recent Advances

Mesoionische N‐Heterocyclische Olefine verschieben die obere Grenze der Nucleophilie‐Skala

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Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO₂ for consecutive N-methylation of amines

Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions