Teck-Peng Loh

Publications of Teck-Peng Loh

• Synthesis and application of a recyclable ionic liquid-supported imidazolidinone catalyst in enantioselective 1,3-dipolar cycloaddition.

  Authors: Zhi-Liang Shen, Kau Kiat Kelvin Goh, Colin Hong An Wong, Wan-Yi Loo, Yong-Sheng Yang, Jun Lu, Teck-Peng Loh

  Chemical communications (Cambridge, England). 05/2012;

  The synthesis of recyclable ionic liquid-supported imidazolidinone catalyst and its application in 1,3-dipolar cycloaddition of nitrone with α,β-unsaturated aldehyde with high performance wereThe synthesis of recyclable ionic liquid-supported imidazolidinone catalyst and its application in 1,3-dipolar cycloaddition of nitrone with α,β-unsaturated aldehyde with high performance were described. Most importantly, the catalyst can be recovered and recycled for up to five runs without observing significant decrease in catalytic activity.

• Palladium-Catalyzed Direct CH Arylation of Enamides with Simple Arenes.

  Authors: Sreekumar Pankajakshan, Yun-He Xu, Jun Kee Cheng, Man Ting Low, Teck-Peng Loh

  Angewandte Chemie (International ed. in English). 04/2012;

  Z only: An atom-economical synthetic route towards arylated Z-enamides through double CH functionalization is described. The Z/E selectivity of the palladium-catalyzed monoarylation is absoluteZ only: An atom-economical synthetic route towards arylated Z-enamides through double CH functionalization is described. The Z/E selectivity of the palladium-catalyzed monoarylation is absolute (step A in scheme), and the molecular complexity of the products can be further endowed by a sequential second arylation, which requires the use of trifluoracetic acid (TFA; step B).

• The acid free asymmetric intermolecular α-alkylation of aldehydes in fluorinated alcohols.

  Authors: Jian Xiao, Kai Zhao, Teck-Peng Loh

  Chemical communications (Cambridge, England). 03/2012; 48(29):3548-50.

  The acid free asymmetric intermolecular α-alkylation of aldehydes with alcohols has been discovered using trifluoroethanol as solvent. This unprecedented system affords the enantioenrichedThe acid free asymmetric intermolecular α-alkylation of aldehydes with alcohols has been discovered using trifluoroethanol as solvent. This unprecedented system affords the enantioenriched functionalized primary alcohols (after NaBH(4) reduction) in high yields and good to excellent enantioselectivities with wide substrate scope in the absence of any acid additive.

• Palladium-catalyzed C-C bond formation of arylhydrazines with olefins via carbon-nitrogen bond cleavage.

  Authors: Ming-Kui Zhu, Jun-Feng Zhao, Teck-Peng Loh

  Organic letters. 11/2011; 13(23):6308-11.

  The unactivated carbon-nitrogen bond of various aryl hydrazines was cleaved under very mild conditions by Pd(0) with the assistance of Pd(II). The in situ generated aryl palladium complex readilyThe unactivated carbon-nitrogen bond of various aryl hydrazines was cleaved under very mild conditions by Pd(0) with the assistance of Pd(II). The in situ generated aryl palladium complex readily takes part in the C-C bond formation with olefins. This study offered a new mode of C-Pd bond formation, which will spur the development of palladium-catalyzed cross-coupling in the future.

• Highly enantioselective intermolecular alkylation of aldehydes with alcohols by cooperative catalysis of diarylprolinol silyl ether with Brønsted acid.

  Authors: Jian Xiao, Kai Zhao, Teck-Peng Loh

  Chemistry, an Asian journal. 09/2011; 6(11):2890-4.

• Indium mediated allylation in peptide and protein functionalization.

  Authors: Jenefer Alam, Thomas H Keller, Teck-Peng Loh

  Chemical communications (Cambridge, England). 08/2011; 47(32):9066-8.

  Indium-mediated allylation has been used in the site-selective functionalization of N-terminal aldehydes of peptides and proteins. This is the first demonstration of indium-mediated C-C bondIndium-mediated allylation has been used in the site-selective functionalization of N-terminal aldehydes of peptides and proteins. This is the first demonstration of indium-mediated C-C bond formation in protein labelling studies under mild and environmentally friendly conditions.

• Rhodium-catalyzed direct ortho C-H olefination of phenol derivatives.

  Authors: Chao Feng, Teck-Peng Loh

  Chemical communications (Cambridge, England). 08/2011; 47(37):10458-60.

  Cationic rhodium complex-catalyzed olefination of phenol derivatives for the direct introduction of an α,β-unsaturated ester appendage is described. In addition, deuterium labelling and kineticCationic rhodium complex-catalyzed olefination of phenol derivatives for the direct introduction of an α,β-unsaturated ester appendage is described. In addition, deuterium labelling and kinetic isotope effect studies were performed to probe the reaction mechanism.

• Base-free palladium-catalyzed Sonogashira coupling using organogold complexes.

  Authors: Sreekumar Pankajakshan, Teck-Peng Loh

  Chemistry, an Asian journal. 06/2011; 6(9):2291-5.

• Copper-catalyzed α-amination of aliphatic aldehydes.

  Authors: Jie-Sheng Tian, Teck-Peng Loh

  Chemical communications (Cambridge, England). 05/2011; 47(19):5458-60.

  A highly efficient copper-catalyzed α-amination of aliphatic aldehydes for the synthesis of α-amino acetals using secondary amines with readily removable protecting groups as a nitrogen source wasA highly efficient copper-catalyzed α-amination of aliphatic aldehydes for the synthesis of α-amino acetals using secondary amines with readily removable protecting groups as a nitrogen source was developed. This reaction can be operated under very mild conditions, affording the desired products in moderate to good yields.

• A facile synthesis of highly substituted five-membered rings: Mukaiyama-aldol-oxonoium-ene (MAOE) domino reaction.

  Authors: Hao Li, Teck-Peng Loh

  Chemistry, an Asian journal. 05/2011; 6(8):1948-51.

• Direct synthesis of ester-containing indium homoenolate and its application in palladium-catalyzed cross-coupling with aryl halide.

  Authors: Zhi-Liang Shen, Kelvin Kau Kiat Goh, Colin Hong An Wong, Yong-Sheng Yang, Yin-Chang Lai, Hao-Lun Cheong, Teck-Peng Loh

  Chemical communications (Cambridge, England). 03/2011; 47(16):4778-80.

  An efficient method for the synthesis of ester-containing indium homoenolate via a direct insertion of indium into β-halo ester in the presence of CuI/LiCl was described. The synthetic utility of theAn efficient method for the synthesis of ester-containing indium homoenolate via a direct insertion of indium into β-halo ester in the presence of CuI/LiCl was described. The synthetic utility of the indium homoenolate was demonstrated by palladium-catalyzed cross-coupling with aryl halides in DMA with wide functional group compatibility.

• Palladium-catalyzed cross-coupling of indium homoenolate with aryl halide with wide functional group compatibility.

  Authors: Zhi-Liang Shen, Yin-Chang Lai, Colin Hong An Wong, Kelvin Kau Kiat Goh, Yong-Sheng Yang, Hao-Lun Cheong, Teck-Peng Loh

  Organic letters. 02/2011; 13(3):422-5.

  An efficient palladium-catalyzed cross-coupling of indium homoenolate with aryl halide is described. The reactions proceeded efficiently in DMA at 100 °C to afford the desired products of β-arylAn efficient palladium-catalyzed cross-coupling of indium homoenolate with aryl halide is described. The reactions proceeded efficiently in DMA at 100 °C to afford the desired products of β-aryl ketones in moderate to good yields. Various important functional groups including COR, COOR, CHO, CN, OH, and NO(2) can be well tolerated in the protocol.

• Copper-catalyzed highly regioselective silylcupration of terminal alkynes to form α-vinylsilanes.

  Authors: Peng Wang, Xue-Liang Yeo, Teck-Peng Loh

  Journal of the American Chemical Society. 02/2011; 133(5):1254-6.

  A highly regioselective synthesis of branched vinylsilanes through silicon-copper additions to terminal alkynes catalyzed by copper(I) was developed using methanol as additive. The correspondingA highly regioselective synthesis of branched vinylsilanes through silicon-copper additions to terminal alkynes catalyzed by copper(I) was developed using methanol as additive. The corresponding vinylsilanes were obtained with excellent branched to linear selectivity of up to 99/1 in good yields.

• A general strategy for the introduction of stereogenic centers bearing a methyl group: total synthesis of sex pheromones.

  Authors: Shun-Yi Wang, Ping Song, Yen-Jin Chin, Teck-Peng Loh

  Chemistry, an Asian journal. 02/2011; 6(2):385-8.

• Direct synthesis of water-tolerant alkyl indium reagents and their application in palladium-catalyzed couplings with aryl halides.

  Authors: Zhi-Liang Shen, Kelvin Kau Kiat Goh, Yong-Sheng Yang, Yin-Chang Lai, Colin Hong An Wong, Hao-Lun Cheong, Teck-Peng Loh

  Angewandte Chemie (International ed. in English). 01/2011; 50(2):511-4.

• A new class of structurally rigid tricyclic chiral secondary amine organocatalyst: highly enantioselective organocatalytic Michael addition of aldehydes to vinyl sulfones.

  Authors: Jian Xiao, Yun-Peng Lu, Yan-Ling Liu, Poh-Shen Wong, Teck-Peng Loh

  Organic letters. 01/2011; 13(5):876-9.

  A new class of chiral secondary amine organocatalyst was rationally designed as an efficient catalyst to catalyze the elusive Michael addition of aldehydes to vinyl sulfones. High yield and excellentA new class of chiral secondary amine organocatalyst was rationally designed as an efficient catalyst to catalyze the elusive Michael addition of aldehydes to vinyl sulfones. High yield and excellent enantioselectivities could be obtained at room temperature without having to resort to high catalyst loading, anhydrous solvents, and low temperatures. Efficient control of enamine conformation and face shielding as well as the rigid nature of the tricyclic skeleton, with an inherent chiral pocket, provide a well-organized chiral environment to effect this elusive reaction efficiently.

• Palladium-catalyzed bisolefination of C-C triple bonds: a facile method for the synthesis of naphthalene derivatives.

  Authors: Chao Feng, Teck-Peng Loh

  Journal of the American Chemical Society. 12/2010; 132(50):17710-2.

  A highly efficient and mild palladium-mediated bisolefination of C-C triple bonds is described for the first time. With different types of olefin employed, this reaction terminates in diverseA highly efficient and mild palladium-mediated bisolefination of C-C triple bonds is described for the first time. With different types of olefin employed, this reaction terminates in diverse fashions. In addition to the merit of using oxygen as the sole oxidant, this reaction exhibits high reactivities and functionality tolerance simultaneously, thus providing a promising method for the synthesis of naphthalene derivatives.

• Total synthesis of Phytophthora mating hormone α1.

  Authors: Shun-Yi Wang, Ping Song, Li-Yan Chan, Teck-Peng Loh

  Organic letters. 10/2010; 12(22):5166-9.

  Total synthesis of Phytophthora mating hormone α1 (1) has been demonstrated. The required stereochemistries (methyl) are achieved by applying CuI-(S)-Tol-BINAP-catalyzed conjugate addition ofTotal synthesis of Phytophthora mating hormone α1 (1) has been demonstrated. The required stereochemistries (methyl) are achieved by applying CuI-(S)-Tol-BINAP-catalyzed conjugate addition of Grignard reagents to α,β-unsaturated esters.

• Synthesis of water-tolerant indium homoenolate in aqueous media and its application in the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling with acid chloride.

  Authors: Zhi-Liang Shen, Kelvin Kau Kiat Goh, Hao-Lun Cheong, Colin Hong An Wong, Yin-Chang Lai, Yong-Sheng Yang, Teck-Peng Loh

  Journal of the American Chemical Society. 10/2010; 132(45):15852-5.

  The first water-tolerant, ketone-type indium homoenolate was synthesized via the oxidative addition of In/InCl(3) to enones. The reaction proceeds exclusively in aqueous media. Both indium andThe first water-tolerant, ketone-type indium homoenolate was synthesized via the oxidative addition of In/InCl(3) to enones. The reaction proceeds exclusively in aqueous media. Both indium and indium(III) chloride are necessary for the smooth conversion of the reaction. Similar results were obtained when InCl or InCl(2) was used in place of In/InCl(3). The synthetic utility of the indium homoenolate was demonstrated through the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling of indium homoenolate with acid chloride.

• Highly enantioselective Cu(I)-Tol-BINAP-catalyzed asymmetric conjugate addition of Grignard reagents to α,β-unsaturated esters.

  Authors: Shun-Yi Wang, Teck-Peng Loh

  Chemical communications (Cambridge, England). 10/2010; 46(46):8694-703.

  The copper-catalyzed conjugate addition (CA) of organometallic reagents to α,β-unsaturated carbonyl compounds is one of the most versatile synthetic methods for the construction of C-C bonds.The copper-catalyzed conjugate addition (CA) of organometallic reagents to α,β-unsaturated carbonyl compounds is one of the most versatile synthetic methods for the construction of C-C bonds. Interestingly, the application of Grignard reagents, which are among the most widely used of organometallic compounds, in asymmetric conjugate addition (CA) reactions has received less attention. Therefore, our group and others have been exploring better catalytic systems to effect the asymmetric 1,4-conjugate addition of Grignard reagents to α,β-unsaturated esters. It is only in the past decade that significant breakthroughs have been made in this field. In our studies, we found that CuI-Tol-BINAP could catalyze the asymmetric conjugate addition (CA) reactions of Grignard reagents, including the addition of MeMgBr to α,β-unsaturated esters to afford the β-methylated esters in good yields with excellent regio- and enantioselectivities. Both enantiomers of the products could be obtained by either using the enantiomers of the chiral Tol-BINAP or by using the geometrical isomer of the starting material. This method is also suitable for other Michael acceptors. In this article, we describe the development of the asymmetric Cu(I)-Tol-BINAP catalyzed 1,4-conjugate addition of Grignard reagents to α,β-unsaturated esters and applications of this chemistry. This method provides a convenient method to synthesize β-alkyl esters with high enantioselectivity or diastereoselectivity using CuI and the inexpensive chiral ligand, Tol-BINAP.