Efficient catalytic systems for the carboxylation of diamines to cyclic ureas using ethylene urea as a promoter

Jin, Sojeong; Khan, Yeasin; Maeng, Jee Hyun; Kim, Young Jin; Hwang, Jeong Hwan; Cheong, Minserk; Lee, Je Seung; Kim, Hoon Sik

doi:10.1016/j.apcatb.2017.02.079

Cited by 20 publications

(27 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…EDA is known to react rapidly with CO 2 , forming the zwitterionic carbamate species (II). [11] We have also confirmed the formation of II by X-ray crystallography and 13 C NMR spectroscopy. The crystal structure of II is shown in Figure 4 (see also Figure S4 and Tables S1-S3 in SI).…”

Section: Mechanistic Considerationsupporting

confidence: 63%

“…These results strongly suggest that the presence of a labile proton in a solvent molecule is necessary, but not sufficient to be a good solvent for the carboxylation of diamines. [11] Comparison of the reactivity of EDA in methanol, NMP, and 2-PY reveals that the solvent of choice for carboxylation should be the one which possesses both proton donating and a proton accepting functional groups. In this context, cyclic amides bearing a peptide group could be regarded as effective solvents because they are able to function as proton shuttles through tautomerization.…”

Section: Spectroscopic Investigationmentioning

confidence: 99%

“…It is worth mentioning here that the carboxylation of EDA to ethylene urea proceeds through a series of protonation-deprotonation steps. [11,12] Therefore, the stabilization of the enol form would enhance the proton donating ability of 2-PY to a certain extent, thereby facilitating the carboxylation of diamines and leading to cyclic ureas. The hydrogen bonding interaction of 2-PY with the carbonation species (I) was further investigated by FT-IR spectroscopy.…”

Section: Spectroscopic Investigationmentioning

confidence: 99%

“…Such proton transfer can be facilitated in the presence of a base catalyst, which is capable of functioning as a proton shuttle. [11,14] In this context, alkali metal salts with a multivalent anion such as carbonate, bicarbonate, or phosphate anion can be regarded as the catalysts of choice because they can simultaneously accept and donate a proton from the carbonation species like I and II. However, for noncatalytic carboxylation reactions to take place smoothly, a solvent must play a role in assisting the proton transfer.…”

Section: Mechanistic Considerationmentioning

confidence: 99%

“…Computational calculations suggest that catalyst-assisted keto-enol tautomerization of the ethylene urea is responsible for the increase of the cyclic urea yields. [11] Being motivated by this result, we have investigated the effects of various tautomerizable compounds on the carboxylation of diamines. In this work, we report that cyclic ureas can be obtained in high yields and selectivities from the non-catalytic carboxylation of diamines using 2-pyrrolidone (2-PY) as a solvent.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Hwang

Han

et al. 2018

Adv Synth Catal

Self Cite

View full text Add to dashboard Cite

Carboxylation reactions of diamines were found to proceed rapidly and non-catalytically, producing corresponding cyclic ureas in excellent yields and selectivities when 2-pyrrolidone (2-PY) was used as a solvent. A similar promoting effect with 2-PY was also observed for the carboxylation of monoamines by carbon dioxide (CO 2 ). Most notably, the carboxylation reactions of mono-and diamines conducted in 2-PY afforded 2-4 times higher yields of corresponding dialkyl ureas and cyclic ureas compared with those in Nmethyl-2-pyrrolidone (NMP). Such a dramatic promoting effect using 2-PY is believed to be associated with the multiple hydrogen bonding interactions between 2-PY and the CO 2 -containing species of amines. Due to such favorable interactions, carboxylation reactions seem to be more facilitated in 2-PY than in NMP.

show abstract

Section: Mechanistic Considerationsupporting

confidence: 63%

Section: Spectroscopic Investigationmentioning

confidence: 99%

Section: Spectroscopic Investigationmentioning

confidence: 99%

Section: Mechanistic Considerationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Hwang

Han

et al. 2018

Adv Synth Catal

Self Cite

View full text Add to dashboard Cite

show abstract

Mechanistic Insights into the Ni‐Catalyzed Reductive Carboxylation of C−O Bonds in Aromatic Esters with CO₂: Understanding Remarkable Ligand and Traceless‐Directing‐Group Effects

Han

Zhao

Jiang

et al. 2018

Chemistry An Asian Journal

View full text Add to dashboard Cite

The mechanism of the Ni -catalyzed reductive carboxylation reaction of C(sp )-O and C(sp )-O bonds in aromatic esters with CO to access valuable carboxylic acids was comprehensively studied by using DFT calculations. Computational results revealed that this transformation was composed of several key steps: C-O bond cleavage, reductive elimination, and/or CO insertion. Of these steps, C-O bond cleavage was found to be rate-determining, and it occurred through either oxidative addition to form a Ni intermediate, or a radical pathway that involved a bimetallic species to generate two Ni species through homolytic dissociation of the C-O bond. DFT calculations revealed that the oxidative addition step was preferred in the reductive carboxylation reactions of C(sp )-O and C(sp )-O bonds in substrates with extended π systems. In contrast, oxidative addition was highly disfavored when traceless directing groups were involved in the reductive coupling of substrates without extended π systems. In such cases, the presence of traceless directing groups allowed for docking of a second Ni catalyst, and the reactions proceed through a bimetallic radical pathway, rather than through concerted oxidative addition, to afford two Ni species both kinetically and thermodynamically. These theoretical mechanistic insights into the reductive carboxylation reactions of C-O bonds were also employed to investigate several experimentally observed phenomena, including ligand-dependent reactivity and site-selectivity.

show abstract

A DFT study on mechanisms of CO₂ coupling with propargylic alcohols using alkali carbonates

Leng

et al. 2019

Int J of Quantum Chemistry

View full text Add to dashboard Cite

The mechanisms of CO2 coupling with the propargylic alcohol using alkali carbonates M2CO3 (M = Li, Na, K, Cs) have been investigated by means of density functional theory calculations. The calculations reveal that the target product tetronic acid (TA) is yielded through two stages: (a) the formation of the α‐alkylidene cyclic carbonate (αACC) intermediate via Cs2CO3‐mediated carboxylative cyclization of the propargylic alcohol with CO2, and (b) the conversion of the αACC intermediate with Cs2CO3 to produce the cesium salt of the TA. Since the overall kinetic barriers for the two stages are comparable and affordable, the excellent chemoselectivity to the TA should be primarily originated from the high thermodynamic stability of the cesium salt of the TA. Moreover, relative to the TA, the possibility to yield the by‐product acyclic carbonate can be excluded due to the both kinetics and thermodynamic inferiority. This result is different from the organic base‐mediated reaction. Alternatively, our calculations predict that CsHCO3 together generated with the cesium salt of the TA might also be an available mediating reagent for the incorporation of CO2 with the propargylic alcohol. Compared to other alkali carbonates M2CO3 (M = Li, Na, K), the stronger basicity of Cs2CO3 and the lower ionic potential of cesium ion can raise the effective concentration of the αACC intermediate, and thus the conversion of the αACC intermediate into the cesium salt of the TA can be achieved with high yield.

show abstract

Efficient catalytic systems for the carboxylation of diamines to cyclic ureas using ethylene urea as a promoter

Cited by 20 publications

References 20 publications

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Mechanistic Insights into the Ni‐Catalyzed Reductive Carboxylation of C−O Bonds in Aromatic Esters with CO₂: Understanding Remarkable Ligand and Traceless‐Directing‐Group Effects

A DFT study on mechanisms of CO₂ coupling with propargylic alcohols using alkali carbonates

Contact Info

Product

Resources

About

Efficient catalytic systems for the carboxylation of diamines to cyclic ureas using ethylene urea as a promoter

Cited by 20 publications

References 20 publications

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Efficient Non‐Catalytic Carboxylation of Diamines to Cyclic Ureas Using 2‐Pyrrolidone as a Solvent and a Promoter

Mechanistic Insights into the Ni‐Catalyzed Reductive Carboxylation of C−O Bonds in Aromatic Esters with CO2: Understanding Remarkable Ligand and Traceless‐Directing‐Group Effects

A DFT study on mechanisms of CO2 coupling with propargylic alcohols using alkali carbonates

Contact Info

Product

Resources

About

Mechanistic Insights into the Ni‐Catalyzed Reductive Carboxylation of C−O Bonds in Aromatic Esters with CO₂: Understanding Remarkable Ligand and Traceless‐Directing‐Group Effects

A DFT study on mechanisms of CO₂ coupling with propargylic alcohols using alkali carbonates