Korea Carbon Capture and Sequestration Randnter

South Korea

Korea Carbon Capture and Sequestration Randnter

South Korea

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Huang J.,Nanyang Technological University | Hong J.-T.,Seoul National University | Hong J.-T.,Korea Carbon Capture and Sequestration Randnter | Hong S.H.,Seoul National University | Hong S.H.,Korea Carbon Capture and Sequestration Randnter
European Journal of Organic Chemistry | Year: 2012

A 1,4-di(2,6-diisopropylphenyl)-1,2,3-triazol-5-ylidene (tzIPr)-based PEPPSI-type palladium complex was developed as an excellent precatalyst for the Suzuki-Miyaura cross-coupling reaction. The complex showed high activity under mild conditions for the cross-coupling reactions between various types of aryl chlorides and aryl boronic acids regardless of the steric and electronic nature of the substrates. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chen C.,Nanyang Technological University | Hong S.H.,Seoul National University | Hong S.H.,Korea Carbon Capture and Sequestration Randnter | Hong S.H.,Nanyang Technological University
Organic Letters | Year: 2012

The ruthenium catalyzed selective sp 3 C-O cleavage with amide formation was reported in reactions of 3-alkoxy-1-propanol derivatives and amines. The cleavage only occurs at the C3-O position even with 3-benzyloxy-1-propanol. Based on the experimental results, O-bound and C-bound Ru enolate complexes were proposed as key intermediates for the unique selective sp 3 C-O bond cleavage in 3-alkoxy-1-propanols. © 2012 American Chemical Society.


Xu X.,Korea Basic Science Institute | Xu X.,Seoul National University | Xu X.,Korea Carbon Capture and Sequestration Randnter | Pooi B.,Korea Basic Science Institute | And 6 more authors.
Angewandte Chemie - International Edition | Year: 2014

The role of CH-π and CF-π interactions in determining the structure of N-heterocyclic carbene (NHC) palladium complexes were studied using 1H NMR spectroscopy, X-ray crystallography, and DFT calculations. The CH-π interactions led to the formation of the cis-anti isomers in 1-aryl-3-isopropylimidazol-2-ylidene-based [(NHC)2PdX2] complexes, while CF-π interactions led to the exclusive formation of the cis-syn isomer of diiodobis(3-isopropyl-1- pentafluorophenylimidazol-2-ylidene) palladium(II). © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xu X.,Seoul National University | Xu X.,Korea Carbon Capture and Sequestration Randnter | Kim S.H.,Seoul National University | Kim S.H.,Korea Carbon Capture and Sequestration Randnter | And 5 more authors.
Organometallics | Year: 2013

Two abnormal N-heterocyclic carbene (aNHC) gold(I) complexes, [(aNHC)AuCl], were prepared from C2-protected imidazolium salts. The air-stable complexes chloro(1-isopropyl-3-methyl-2,4-diphenylimidazol-5-ylidene)gold(I) (5) and chloro(1,4-diisopropyl-3-methyl-2-phenylimidazol-5-ylidene)gold(I) (6) were synthesized via transmetalation using (SMe2)AuCl and the corresponding silver salt such as [(aNHC)AgI] or [(aNHC)2Ag][I] and were fully characterized by NMR and mass spectroscopy and by X-ray crystallography. To investigate the structure, bonding, and catalytic activity of the aNHC-based Au complexes in comparison with their traditional NHC analogues, the sterically similar NHC-based Au complexes chloro(1,3- diisopropylimidazol-2-ylidene)gold(I) (7) and chloro(3-isopropyl-1- phenylimidazol-2-ylidene)gold(I) (8) were prepared from 1,3- diisopropylimidazolium iodide (3) and 3-isopropyl-1-phenylimidazolium iodide (4), respectively. X-ray crystallography and density functional theory (DFT) calculations showed that the aNHC complexes have longer Au-Ccarbene bond distances than the NHC complexes. Furthermore, DFT calculations predicted that, despite their longer Au-Ccarbene distances, aNHC complexes have stronger binding energies. It is suggested on the basis of additional theoretical analyses that these counterintuitive trends can be rationalized by considering individual factors that comprise the molecular interaction. The efficient back-donation of electrons and the smaller overlap repulsion in NHC complexes render the Au-Ccarbene distance shorter, whereas the stronger Au-Ccarbene bonding in the aNHC-Au complexes is attributed to the greater electrostatic attraction and the higher electron-donating ability of the carbene lone pair orbital. Catalytic activities of the NHC-based Au complexes were also compared in the alkyne hydration. Traditional NHC-based Au complexes exhibited higher efficiency in the reaction. © 2012 American Chemical Society.


Ji M.,Ajou University | Lim S.,Ajou University | Jang H.-Y.,Ajou University | Jang H.-Y.,Korea Carbon Capture and Sequestration Randnter
RSC Advances | Year: 2014

N-heterocyclic carbene-catalyzed oxidation using TEMPO is reported for the conversion of aldehydes to amides. A wide range of amides were synthesized in good yields (up to 72%) via a one-pot, sequential protocol involving oxidative esterification of aldehydes and subsequent aminolysis. To promote efficient aminolysis, various alkoxide leaving groups were evaluated. © 2014 the Partner Organisations.


Kang Y.-W.,Ajou University | Jang H.-Y.,Ajou University | Jang H.-Y.,Korea Carbon Capture and Sequestration Randnter
RSC Advances | Year: 2014

A combination of N-heterocyclic carbene (NHC) catalysts and 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) was proposed for the synthesis of allylic esters from allylic alcohols. The yield of one-pot conversion of allylic alcohols to esters increased when hexafluoroisopropanol (HFIP) was used. The effect of HFIP in this tandem reaction was investigated by monitoring the reaction using gas chromatographic analysis. Control experiments using oxoammonium showed that the oxidative esterification occurred via a single-electron transfer mechanism. © 2014 the Partner Organisations.


Lee C.,Ajou University | Lim Y.N.,Ajou University | Jang H.-Y.,Ajou University | Jang H.-Y.,Korea Carbon Capture and Sequestration Randnter
European Journal of Organic Chemistry | Year: 2015

Recent remarkable success of copper-catalyzed oxidative bond formations led us to develop an environmentally benign copper-catalyzed sulfur-nitrogen bond-forming reaction to provide synthetically and industrially useful electron-deficient sulfenamides. The low nucleophilicity of N-formyl/acyl- and sulfonylamides was overcome by introducing a 1,5,7-triazabicyclo[4.4.0]dec-5-ene additive. A variety of N-formyl/acylsulfenamides and -thiosulfonamides were synthesized in good yields without over-oxidation of sulfur. Related mechanistic studies supported the proposed reaction mechanism. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lee C.,Ajou University | Wang X.,Ajou University | Jang H.-Y.,Ajou University | Jang H.-Y.,Korea Carbon Capture and Sequestration Randnter
Organic Letters | Year: 2015

Despite the remarkable success of the copper-catalyzed oxidative coupling reaction, direct cross-coupling of amines and thiols for the synthesis of N-sulfenylimines has not been previously reported. Using commercially available copper catalysts (CuI) and oxygen as an environmentally benign oxidant, synthetically useful N-sulfenylimines were prepared from amines and thiols in good yields without overoxidation of sulfur atoms. © 2015 American Chemical Society.


Ji M.,Ajou University | Wang X.,Ajou University | Lim Y.N.,Ajou University | Kang Y.-W.,Ajou University | And 2 more authors.
European Journal of Organic Chemistry | Year: 2013

A versatile carbene-catalysed oxidation protocol involving N-heterocyclic carbene catalysts and 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) is described for the synthesis of esters, cinnamic acids, and thioesters. A wide range of esters, thioesters, and cinnamic acids were obtained by metal-free coupling of aldehydes with aliphatic, allylic and aromatic alcohols, benzyl mercaptan, and water. In addition to the oxidative coupling of aldehydes with nucleophiles, dehydrogenation of saturated aldehydes and oxidation of allylic alcohols were found under our oxidative coupling conditions. Unlike other TEMPO-mediated oxidative esterification reactions, this reaction does not proceed through a TEMPO ester intermediate to form esters and thioesters. N-Heterocyclic carbene complexes catalyse various oxidative coupling reactions in the presence of TEMPO. A variety of α,β-unsaturated and saturated esters, and aromatic esters and thioesters were synthesised. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang X.,Ajou University | Lim Y.N.,Ajou University | Lee C.,Ajou University | Jang H.-Y.,Ajou University | And 3 more authors.
European Journal of Organic Chemistry | Year: 2013

Direct carboxylation of acetylene with CO2 was carried out in the presence of 1,5,7-triazabicyclo[4.4.0]dec-1-ene (TBD); subsequent reduction of dicarboxylated acetylene produces commercially valuable succinate salts. This metal-free carboxylation has potential economic and environmental impact by utilizing non-petroleum feedstocks (acetylene) and CO2 and by producing valuable chemical feed stocks. Direct carboxylation of acetylene with CO2 was carried out in the presence of 1,5,7-triazabicyclo[4.4.0]dec- 1-ene (TBD); subsequent reduction of dicarboxylated acetylene produces commercially valuable succinate salts. This metal-free carboxylation has potential economic and environmental impact by utilizing non-petroleum feedstocks (acetylene) and CO2 and by producing valuable chemical feed stocks. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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