Sukwon Hong

Publications of Sukwon Hong

• Urea/transition-metal cooperative catalyst for anti-selective asymmetric nitroaldol reactions.

  Authors: Kai Lang, Jongwoo Park, Sukwon Hong

  Angewandte Chemie (International ed. in English). 02/2012; 51(7):1620-4.

  A cooperative catalyst that features urea H-bonding and a cobalt center was developed for anti-selective asymmetric Henry reactions. The H-bonds of urea play a crucial role in the improvement inA cooperative catalyst that features urea H-bonding and a cobalt center was developed for anti-selective asymmetric Henry reactions. The H-bonds of urea play a crucial role in the improvement in yield (from 30 % to 84 %), enantioselectivity (from 78 % to 96 %), and anti diastereoselectivity (from 3:1 to 48:1). A short synthesis of (1R,2S)-methoxamine hydrochloride was also accomplished with this catalyst.

• Self-assembly approach toward chiral bimetallic catalysts: bis-urea-functionalized (salen)cobalt complexes for the hydrolytic kinetic resolution of epoxides.

  Authors: Jongwoo Park, Kai Lang, Khalil A Abboud, Sukwon Hong

  Chemistry (Weinheim an der Bergstrasse, Germany). 02/2011; 17(7):2236-45.

  A series of novel bis-urea-functionalized (salen)Co complexes has been developed. The complexes were designed to form self-assembled structures in solution through intermolecular urea-ureaA series of novel bis-urea-functionalized (salen)Co complexes has been developed. The complexes were designed to form self-assembled structures in solution through intermolecular urea-urea hydrogen-bonding interactions. These bis-urea (salen)Co catalysts resulted in rate acceleration (up to 13 times) in the hydrolytic kinetic resolution (HKR) of rac-epichlorohydrin in THF by facilitating cooperative activation, compared to the monomeric catalyst. In addition, one of the bis-urea (salen)Co(III) catalyst efficiently resolves various terminal epoxides even under solvent-free conditions by requiring much shorter reaction time at low catalyst loading (0.03-0.05 mol %). A series of kinetic/mechanistic studies demonstrated that the self-association of two (salen)Co units through urea-urea hydrogen bonds was responsible for the observed rate acceleration. The self-assembly study with the bis-urea (salen)Co by FTIR spectroscopy and with the corresponding (salen)Ni complex by (1)H NMR spectroscopy showed that intermolecular hydrogen-bonding interactions exist between the bis-urea scaffolds in THF. This result demonstrates that self-assembly approach by using non-covalent interactions can be an alternative and useful strategy toward the efficient HKR catalysis.

• Isoquinoline-based chiral monodentate N-heterocyclic carbenes.

  Authors: Dimitri Hirsch-Weil, Khalil A Abboud, Sukwon Hong

  Chemical communications (Cambridge, England). 10/2010; 46(40):7525-7.

  C(1)-symmetric isoquinoline-based chiral diaminocarbene ligands (MIQ) have been developed to block three quadrants of the metal coordination sphere, complementing C(2)-symmetric biisoquinoline-basedC(1)-symmetric isoquinoline-based chiral diaminocarbene ligands (MIQ) have been developed to block three quadrants of the metal coordination sphere, complementing C(2)-symmetric biisoquinoline-based ligands (BIQ). MIQ-Cu complexes catalyzed conjugate borylation of various α,β-unsaturated amides in good yields (82-99%) and enantioselectivities (75-87% ee).

• Novel acyclic diaminocarbene ligands with increased steric demand and their application in gold catalysis.

  Authors: Hwimin Seo, Benjamin P Roberts, Khalil A Abboud, Kenneth M Merz, Sukwon Hong

  Organic letters. 10/2010; 12(21):4860-3.

  Sterically demanding and conformationally stable N,N'-ditertiaryalkyl-N,N'-diphenyl acyclic diaminocarbenes (ADCs) were developed. Bulky ADC-Au catalysts not only showed competitive reactivities inSterically demanding and conformationally stable N,N'-ditertiaryalkyl-N,N'-diphenyl acyclic diaminocarbenes (ADCs) were developed. Bulky ADC-Au catalysts not only showed competitive reactivities in hydroamination and enyne cyclization but also demonstrated unique ligand properties different from bulky N-heterocyclic carbene (NHC) counterparts.

• Development of bifunctional aza-bis(oxazoline) copper catalysts for enantioselective Henry reaction.

  Authors: Kai Lang, Jongwoo Park, Sukwon Hong

  The Journal of organic chemistry. 10/2010; 75(19):6424-35.

  Base-functionalized aza-bis(oxazoline) ligands were prepared to explore the concept of dual activation through the Lewis acid and a tethered tertiary amine base. The catalytic activity of the CuBase-functionalized aza-bis(oxazoline) ligands were prepared to explore the concept of dual activation through the Lewis acid and a tethered tertiary amine base. The catalytic activity of the Cu complex was evaluated for the asymmetric Henry reaction. Compared with a corresponding unfunctionalized copper complex with external 1-benzyl-4-ethylpiperazine base, the ethylpiperazine-functionalized aza-bis(oxazoline) copper catalyst resulted in rate acceleration (2.5 times) as well as improved enantioselectivity (72% ee vs 92% ee).

• A New Route to Acyclic Diaminocarbenes via Lithium-Halogen Exchange.

  Authors: David R Snead, Ion Ghiviriga, Khalil A Abboud, Sukwon Hong

  Organic letters. 08/2009;

  A lithium-halogen exchange route has been developed to generate acyclic diaminocarbenes (ADC) from chloroamidinium salts. Convenient access to various ADC complexes (B, Rh, Ir, Pd) stems from aA lithium-halogen exchange route has been developed to generate acyclic diaminocarbenes (ADC) from chloroamidinium salts. Convenient access to various ADC complexes (B, Rh, Ir, Pd) stems from a one-pot transmetalation protocol. Formation of a carbenoid species is suggested by 1D and 2D NMR studies with a (13)C-labeled chloroamidinium precursor and also by X-ray structures of transition metal-carbene complexes. Rh-ADC complex 4 is an effective catalyst for the 1,2-addition of aryl boronic acids to aryl aldehydes.

• In situ generation of novel acyclic diaminocarbene-copper complex.

  Authors: Dimitri Hirsch-Weil, David R Snead, Sebastien Inagaki, Hwimin Seo, Khalil A Abboud, Sukwon Hong

  Chemical communications (Cambridge, England). 06/2009;

  A novel acyclic diaminocarbene-copper complex appears to be generated from a chloroamidinium salt and Cu(i)-thiophenecarboxylate in the presence of Grignard reagent based on (13)C NMR studies and isA novel acyclic diaminocarbene-copper complex appears to be generated from a chloroamidinium salt and Cu(i)-thiophenecarboxylate in the presence of Grignard reagent based on (13)C NMR studies and is a highly efficient catalyst for S(N)2'-allylic alkylation.

• Self-assembled dinuclear cobalt(II)-salen catalyst through hydrogen-bonding and its application to enantioselective nitro-aldol (Henry) reaction.

  Authors: Jongwoo Park, Kai Lang, Khalil A Abboud, Sukwon Hong

  Journal of the American Chemical Society. 01/2009; 130(49):16484-5.

• Development of biisoquinoline-based chiral diaminocarbene ligands: enantioselective SN2' allylic alkylation catalyzed by copper-carbene complexes.

  Authors: Hwimin Seo, Dimitri Hirsch-Weil, Khalil A Abboud, Sukwon Hong

  The Journal of organic chemistry. 04/2008; 73(5):1983-6.

  Chiral biisoquinoline-based diaminocarbene ligands (BIQ) were designed to create a chiral environment extended toward the metal center, which was confirmed by an X-ray structure. The concise ligandChiral biisoquinoline-based diaminocarbene ligands (BIQ) were designed to create a chiral environment extended toward the metal center, which was confirmed by an X-ray structure. The concise ligand synthesis is highlighted by a modified Bischler-Napieralski cyclization of bisamides prepared from readily available chiral phenethylamines, and allows easy variation of the stereodifferentiating groups. The cyclohexyl-BIQ-copper complex is an efficient catalyst for enantioselective SN2' allylic alkylation with Grignard reagents showing SN2' regioselectivity higher than 5:1 and enantioselectivity in the range of 68-77% ee.