Yong-chua Teo

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Organization: National Institute of Education

Department: Natural Sciences and Science Education

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TOPICS

Organic Chemistry

C-H Activation

Chemicals
References

Regioselective copper-diamine-catalyzed C–H arylation of 1,2,4-triazole ring with aryl bromides

Co-reporter:Zaini Jamal and Yong-Chua Teo

RSC Advances 2016 vol. 6(Issue 79) pp:75449-75452

Publication Date(Web):27 Jul 2016

DOI:10.1039/C6RA14670H

A convenient methodology for the regioselective C–H arylation of 1,2,4-triazole ring was developed. Using a benchtop stable Cu-diamine catalyst system, C–H functionalization of a simple 1,2,4-triazole substrate with various aryl bromides was regioselectively accomplished at the C5 position of the triazole ring.

Mild ligand-free Cu0-catalyzed chemoselective S-arylation of 2-mercaptoimidazole at low catalyst loading

Co-reporter:Bryan Yong-Hao Tan, Yong-Chua Teo

Tetrahedron 2016 Volume 72(Issue 42) pp:6646-6653

Publication Date(Web):20 October 2016

DOI:10.1016/j.tet.2016.08.085

A mild method for the Cu0-catalyzed chemoselective CS cross-coupling of 2-mercaptoimidazole derivatives with a series of with differently substituted iodobenzenes and iodothiophenes at 100 °C is described. This method proceeds efficiently without ligands and at low catalyst loading (3 mol %), without the need for stringent inert conditions. Under optimized conditions, the S-arylated products were obtained in good yields of up to 90%.Download full-size image

Direct alkenylation of alkylazaarenes with aldehydes through C(sp3)–H functionalization under catalytic InCl3 activation

Co-reporter:Zaini Jamal, Yong-Chua Teo, Gina Shiyun Lim

Tetrahedron 2016 Volume 72(Issue 17) pp:2132-2138

Publication Date(Web):28 April 2016

DOI:10.1016/j.tet.2016.03.004

Under the influence of InCl3 as a Lewis acid catalyst, a methodology on the C(sp3)–H functionalization of alkylazaarenes has been demonstrated through the activation of benzylic C–H bonds towards their addition reaction with the appropriate electrophiles. This methodology was chiefly applied in the direct alkenylation of primary and secondary benzylic C–H bonds of alkylazaarenes with aldehydes. A variety of alkenyl products were afforded in generally good yields including the starting alkenyl intermediate used in the synthesis of montelukast and other related molecules.

Indium-catalyzed C(sp3)–H functionalization of 2-methylazaarenes through direct benzylic addition to trifluoromethyl ketones

Co-reporter:Zaini Jamal and Yong-Chua Teo

RSC Advances 2015 vol. 5(Issue 34) pp:26949-26953

Publication Date(Web):10 Mar 2015

DOI:10.1039/C4RA17182A

The application of trivalent indium for the Lewis acid-catalyzed C(sp3)–H functionalization of 2-methylazaarenes is reported. InCl3 was discovered to catalyze the direct addition of the benzylic C–H bond in the azaarenes to trifluoromethyl ketones. An ample number of substrates were cogently demonstrated to give the products as trifluoromethylated alcohols whereby in some cases, up to quantitative yield (99%) could be obtained.

Efficient cobalt-catalyzed C–N cross-coupling reaction between benzamide and aryl iodide in water

Co-reporter:Bryan Yong-Hao Tan and Yong-Chua Teo

Organic & Biomolecular Chemistry 2014 vol. 12(Issue 38) pp:7478-7481

Publication Date(Web):2014/08/11

DOI:10.1039/C4OB01483A

A practical and efficient strategy for the N-arylation of benzamide catalysed by a Co(C2O4)·2H2O/dmeda system in water is reported. Under the optimized conditions, a wide variety of N-arylated products were obtained in good yields (up to 92%) using substituted aryl iodides.

Functionalization of the Benzylic CH Bonds in Azaarenes by Cobalt-Catalyzed 1,4-Addition to Enones

Co-reporter:Zaini Jamal;Ling-Keong Wong

European Journal of Organic Chemistry 2014 Volume 2014( Issue 33) pp:7343-7346

Publication Date(Web):

DOI:10.1002/ejoc.201403203

Abstract

Functionalization of the C(sp³)–H bonds in azaarenes was catalyzed by CoCl₂ as an inexpensive Lewis acid catalyst. Enones were demonstrated to be good C=C electrophilic acceptors for the construction of various azaarene-containing 1,4-addition products in yields of up to 95 %.

Low Catalyst Loadings for Ligand-Free Copper(I)-Oxide-Catalyzed N-Arylation of Methanesulfonamide in Water

Co-reporter:Bryan Yong-Hao Tan, ;Ai-Hua Seow

European Journal of Organic Chemistry 2014 Volume 2014( Issue 7) pp:1541-1546

Publication Date(Web):

DOI:10.1002/ejoc.201301561

Abstract

A simple and practical protocol for the cross-coupling of methanesulfonamide and aryl iodides under ligand-free copper(I)-oxide-catalyzed conditions in water is reported. The method allows the preparation of a wide variety of synthetically useful N-arylated methanesulfonamides in good to excellent yields (up to 90 %) under the optimized conditions.

Efficient Manganese/Copper Bimetallic Catalyst for N-Arylation of Amides and Sulfonamides Under Mild Conditions in Water

Co-reporter:Yong-Chua Teo;Fui-Fong Yong;Idzham Khalid Ithnin;Siew-Hui Trionna Yio ;Zhiyin Lin

European Journal of Organic Chemistry 2013 Volume 2013( Issue 3) pp:515-524

Publication Date(Web):

DOI:10.1002/ejoc.201201218

Abstract

An efficient and mild method using a bimetallic MnF₂/CuI catalyst at 60 °C in water was developed for the N-arylation of amides and sulfonamides with aryl halides. A variety of functionalized amides and sulfonamides were coupled with different substituted aryl halides to afford the corresponding N-arylated products in good to excellent yields (up to 97 %).

Efficient copper-catalyzed cross-coupling of 1-Boc-piperazine with aryl iodides and its application in the synthesis of trazodone

Co-reporter:Fui-Fong Yong, Yong-Chua Teo, Khee-Ngiap Tan

Tetrahedron Letters 2013 Volume 54(Issue 39) pp:5332-5334

Publication Date(Web):25 September 2013

DOI:10.1016/j.tetlet.2013.07.104

A convenient and practical strategy is developed for the cross-coupling of N-Boc protected piperazines with aryl iodides using CuBr/1,1′-bi-2-naphthol as the catalyst and K3PO4 as the base. The protocol affords N-arylated piperazine products in moderate to good yields under the optimized conditions. The application of this catalytic system to the synthesis of trazodone is also successfully demonstrated using commercially available substrates.A convenient and practical strategy is developed for the cross-coupling of N-Boc protected piperazines with aryl iodides using CuBr/1,1′-bi-2-naphthol as the catalyst and K3PO4 as the base. The protocol affords N-arylated piperazine products in moderate to good yields under the optimized conditions. The application of this catalytic system to the synthesis of trazodone is also successfully demonstrated using commercially available substrates.

Ligand-free Cu2O-catalyzed cross coupling of nitrogen heterocycles with iodopyridines

Co-reporter:Yong-Chua Teo, Fui-Fong Yong, Shirlyn Sim

Tetrahedron 2013 69(35) pp: 7279-7284

Publication Date(Web):

DOI:10.1016/j.tet.2013.06.095

Efficient ligand-free copper-catalyzed N-arylation of amides with aryl halides in water

Co-reporter:Fui-Fong Yong, Yong-Chua Teo, Guan-Leong Chua, Gina Shiyun Lim, Yizhen Lin

Tetrahedron Letters 2011 Volume 52(Issue 11) pp:1169-1172

Publication Date(Web):16 March 2011

DOI:10.1016/j.tetlet.2011.01.003

A convenient and efficient protocol has been developed for the cross-coupling of amides and aryl iodides using a ligand-free copper(I) oxide catalyst in water. A variety of amide derivatives afforded the corresponding N-arylated products in moderate to good yields (up to 88%).A convenient and efficient protocol has been developed for the cross-coupling of amides and aryl iodides using a ligand-free copper(I) oxide catalyst in water. A variety of amide derivatives afforded the corresponding N-arylated products in moderate to good yields (up to 88%).

A ligand-free copper(I) oxide catalyzed strategy for the N-arylation of azoles in water

Co-reporter:Fui-Fong Yong, Yong-Chua Teo, Siew-Hoon Tay, Bryan Yong-Hao Tan, Kim-Huat Lim

Tetrahedron Letters 2011 Volume 52(Issue 11) pp:1161-1164

Publication Date(Web):16 March 2011

DOI:10.1016/j.tetlet.2011.01.005

A simple and practical protocol has been developed for the cross-coupling of azoles and aryl iodides under ligand-free copper(I) oxide catalyzed conditions in water. The protocol uses tetrabutylammonium bromide (TBAB) as the phase-transfer catalyst, and water as the solvent, and shows good tolerance towards various functional groups.A simple and practical protocol has been developed for the cross-coupling of azoles and aryl iodides under ligand-free copper(I) oxide catalyzed conditions in water. The protocol uses tetrabutylammonium bromide (TBAB) as the phase-transfer catalyst, and water as the solvent, and shows good tolerance towards various functional groups.

A manganese/copper bimetallic catalyst for C–N coupling reactions under mild conditions in water

Co-reporter:Yong-Chua Teo, Fui-Fong Yong, Gina Shiyun Lim

Tetrahedron Letters 2011 Volume 52(Issue 52) pp:7171-7174

Publication Date(Web):28 December 2011

DOI:10.1016/j.tetlet.2011.10.128

An efficient and convenient bimetallic MnF2/CuI catalyst in combination with trans-1,2-diaminocyclohexane has been developed for the cross-coupling of nitrogen heterocycles with aryl halides in water at moderate temperature. A variety of nitrogen nucleophiles including pyrazole, 7-azaindole, indazole, indole, pyrrole and imidazole afforded the corresponding products in moderate to good yields (up to 94%) under the described arylation conditions.An efficient and convenient bimetallic MnF2/CuI catalyst in combination with trans-1,2-diaminocyclohexane has been developed for the cross-coupling of nitrogen heterocycles with aryl halides in water.

Manganese-catalyzed cross-coupling reactions of aliphatic amines with aryl halides

Co-reporter:Fui-Fong Yong, Yong-Chua Teo

Tetrahedron Letters 2010 Volume 51(Issue 30) pp:3910-3912

Publication Date(Web):28 July 2010

DOI:10.1016/j.tetlet.2010.05.098

An efficient and convenient protocol has been developed for the N-arylation of aliphatic amines with differently substituted aryl halides using a MnCl2·4H2O/l-proline catalyst and NaOt-Bu as the base in DMSO.An efficient and convenient protocol has been developed for the N-arylation of aliphatic amines with differently substituted aryl halides using a MnCl2·4H2O/l-proline catalyst and NaOt-Bu as the base in DMSO.

Manganese-catalyzed cross-coupling reactions of nitrogen nucleophiles with aryl halides in water

Co-reporter:Yong-Chua Teo, Fui-Fong Yong, Chai-Yun Poh, Yaw-Kai Yan and Guan-Leong Chua

Chemical Communications 2009 (Issue 41) pp:6258-6260

Publication Date(Web):28 Aug 2009

DOI:10.1039/B909803H

A facile and convenient strategy for the assembly of N-arylated heterocycles has been demonstrated using a MnCl2·4H2O/trans-1,2-diaminocyclohexane catalyst and K3PO4 as the base in water.

Efficient Cross-Coupling Reactions of Nitrogen Nucleophiles with Aryl Halides in Water

Co-reporter:Yong-Chua Teo

Advanced Synthesis & Catalysis 2009 Volume 351( Issue 9) pp:

Publication Date(Web):

DOI:10.1002/adsc.200990017

No abstract is available for this article.

Efficient Cross-Coupling Reactions of Nitrogen Nucleophiles with Aryl Halides in Water

Co-reporter:Yong-Chua Teo

Advanced Synthesis & Catalysis 2009 Volume 351( Issue 5) pp:720-724

Publication Date(Web):

DOI:10.1002/adsc.200800746

Cobalt-Catalyzed N-Arylation of Nitrogen Nucleophiles in Water

Co-reporter:Yong-Chua Teo Dr.;Guan-Leong Chua Dr.

Chemistry - A European Journal 2009 Volume 15( Issue 13) pp:3072-3075

Publication Date(Web):

DOI:10.1002/chem.200802483

Organocatalytic asymmetric syn-selective direct aldol reactions in water

Co-reporter:Yong-Chua Teo, Guan-Leong Chua, Chin-Yee Ong, Chai-Yun Poh

Tetrahedron Letters 2009 50(34) pp: 4854-4856

Publication Date(Web):

DOI:10.1016/j.tetlet.2009.06.037

Direct asymmetric three-component Mannich reactions catalyzed by a siloxy serine organocatalyst in water

Co-reporter:Yong-Chua Teo, Jun-Jie Lau, Man-Chao Wu

Tetrahedron: Asymmetry 2008 Volume 19(Issue 2) pp:186-190

Publication Date(Web):6 February 2008

DOI:10.1016/j.tetasy.2007.12.011

A siloxy-l-serine organocatalyst has been developed to catalyze the asymmetric three-component Mannich reactions in the presence of water via a biphasic system, furnishing the Mannich products in good yields and high enantioselectivities.(2S)-2-Benzyloxycarbonylamino-3-(tert-butyl-diphenyl-silanyloxy)-propionic acidC19H25NO3Si[α]D23=+2.6 (c 1.94, MeOH)Source of chirality: Z-Serine-OHAbsolute configuration: (S)

Direct asymmetric aldol reactions catalyzed by a siloxy serine organocatalyst in water

Co-reporter:Yong-Chua Teo

Tetrahedron: Asymmetry 2007 Volume 18(Issue 10) pp:1155-1158

Publication Date(Web):11 June 2007

DOI:10.1016/j.tetasy.2007.05.025

A siloxy-l-serine organocatalyst has been developed to catalyze direct asymmetric aldol reactions in the presence of water, furnishing the β-hydroxy carbonyl scaffold in high enantio- and diastereoselectivities. The direct aldol reaction between a selection of aromatic aldehydes and cyclohexanone resulted in good yields and high enantioselectivities.A siloxy-l-serine organocatalyst has been developed to catalyze the asymmetric direct aldol reactions in the presence of water, furnishing the β-hydroxy carbonyl scaffold in high enantio- and diastereoselectivities. The direct aldol reaction between a selection of aromatic aldehydes and cyclohexanone resulted in good yields and high enantioselectivities.

Efficient cobalt-catalyzed C–N cross-coupling reaction between benzamide and aryl iodide in water

Co-reporter:Bryan Yong-Hao Tan and Yong-Chua Teo

Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 38) pp:NaN7481-7481

Publication Date(Web):2014/08/11

DOI:10.1039/C4OB01483A

Manganese-catalyzed cross-coupling reactions of nitrogen nucleophiles with aryl halides in water

Co-reporter:Yong-Chua Teo, Fui-Fong Yong, Chai-Yun Poh, Yaw-Kai Yan and Guan-Leong Chua

Chemical Communications 2009(Issue 41) pp:NaN6260-6260

Publication Date(Web):2009/08/28

DOI:10.1039/B909803H

A facile and convenient strategy for the assembly of N-arylated heterocycles has been demonstrated using a MnCl2·4H2O/trans-1,2-diaminocyclohexane catalyst and K3PO4 as the base in water.