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  • 1. Chakka, Sai Kumar
    et al.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Maguire, Glenn E. M.
    Kruger, Hendrik G.
    Govender, Thavendran
    Synthesis and Screening of C-1-Substituted Tetrahydroisoquinoline Derivatives for Asymmetric Transfer Hydrogenation Reactions2010In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 5, p. 972-980Article in journal (Refereed)
    Abstract [en]

    Tetrahydroisoquinoline (TIQ) derivatives exhibit good biological activity. However, utilization of TIQ compounds in asymmetric catalysis is limited. This paper presents a series of TIQ derivatives in asymmetric transfer hydrogenation (ATH) reactions. Chiral TIQ amino alcohol ligands were synthesized and screened for the ATH reaction of aromatic ketones. The effect of a cis- and trans-phenyl substitution at the C-1 position on the ligand backbone was investigated both experimentally and computationally. The results showed that the trans orientation on the TIQ scaffold yields higher turnover rates with a selectivity of 94% ee obtained at room temperature with an Ru complex. The cis isomer results in a high turnover rate with no selectivity. The trans isomer gave 99% ee at lower temperatures. Furthermore, it was observed that substitution at the C-3-alpha position results in a drop of the enantioselectivity and the reactivity of the catalyst.

  • 2. Chakka, Sai Kumar
    et al.
    Peters, Byron K.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Maguire, Glenn E. M.
    Kruger, Hendrik G.
    Govender, Thavendran
    Iridium-catalyzed asymmetric hydrogenation of olefins using TIQ phosphine-oxazoline ligands2010In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 21, no 18, p. 2295-2301Article in journal (Refereed)
    Abstract [en]

    A novel family of tetrahydroisoquinoline (TIQ) phosphine-oxazoline ligands and four corresponding iridium complexes have been developed and applied to the asymmetric hydrogenation of unfunctionalized olefins. The results showed that the best conversion rates were observed in up to 99% with an enantiomeric excess of 91%.

  • 3. Kawthekar, Rahul B.
    et al.
    Chakka, Sai Kumar
    Francis, Vivian
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Kruger, Hendrik G.
    Maguire, Glenn E. M.
    Govender, Thavendran
    Synthesis of tetrahydroisoquinoline (TIQ)-oxazoline ligands and their application in enantioselective Henry reactions2010In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 21, no 7, p. 846-852Article in journal (Refereed)
    Abstract [en]

    A novel family of eleven new tetrahydroisoquinoline (TIQ)-oxazoline intermediates and five corresponding copper(II) catalysts has been developed and applied to the catalytic asymmetric Henry reaction of various aldehydes with nitromethane to provide beta-hydroxy nitroalkanes in high conversion (>99%) This paper describes the synthesis of the TIQ compounds from L-dihydroxyphenylalanine (L-DOPA) as the starting material The chiral ligands were complexed in situ with various transition metals such as Cu, Sc, Co, Zn, Ni and Mn and tested as a chiral catalyst for the Henry reaction The reaction was optimized in terms of the metal, counter ion, solvent, temperature and over a range of substrates The corresponding catalyst with copper(II) acetate and 2-propanol as the solvent provides the best enantioselectivities (up to 77% ee) of the corresponding nitroalcohol for 4-chlorobenzaldehyde.

  • 4.
    Li, Jia-Qi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Paptchikhine, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Govender, Thavendran
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Bicyclic phosphine-thiazole ligands for the asymmetric hydrogenation of olefins2010In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 21, no 11-12, p. 1328-1333Article in journal (Refereed)
    Abstract [en]

    New bicyclic thiazole-based chiral N,P-chelating ligands were developed. High activities and enantioselectivities were achieved in the iridium-catalyzed asymmetric hydrogenation of olefins with the new ligands.

  • 5.
    Mazuela, Javier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Paptchikhine, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Pàmies, Oscar
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Diéguez, Montserrat
    Adaptative Biaryl Phosphite-Oxazole and Phosphite-Thiazole Ligands for Asymmetric Ir-Catalyzed Hydrogenation of Alkenes2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 15, p. 4567-4576Article in journal (Refereed)
    Abstract [en]

    A library of readily available phosphite-oxazole/thiazole ligands (L1 a-g-L7 a-g) was applied in the Ir-catalyzed asymmetric hydrogenation of several largely unfunctionalized E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridge length, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety), so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99 %) for a wide range of E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility.

  • 6. Mazuela, Javier
    et al.
    Paptchikhine, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Tolstoy, Päivi
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Pàmies, Oscar
    Diéguez, Montserrat
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    A new class of modular P,N-ligand library for asymmetric Pd-catalyzed allylic substitution reactions: a study of the key Pd-pi-allyl intermediates2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 2, p. 620-638Article in journal (Refereed)
    Abstract [en]

    A new class of modular P,N-ligand library has been synthesized and screened in the Pd-catalyzed allylic substitution reactions of several substrate types. These series of ligands can be prepared efficiently from easily accessible hydroxyl-oxazole/thiazole derivatives. Their modular nature enables the bridge length, the substituents at the heterocyclic ring and in the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety to be easily and systematically varied. By carefully selecting the ligand components, therefore, high regio- and enantioselectivities (ee values up to 96 %) and good activities are achieved in a broad range of mono-, di-, and trisubstituted linear hindered and unhindered substrates and cyclic substrates. The NMR spectroscopic and DFT studies on the Pd-pi-allyl intermediates provide a deeper understanding of the effect of ligand parameters on the origin of enantioselectivity.

  • 7. Peters, Byron K.
    et al.
    Chakka, Sai Kumar
    Naicker, Tricia
    Maguire, Glenn E. M.
    Kruger, Hendrik G.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Govender, Thavendran
    Synthesis of tetrahydroisoquinoline-diamine ligands and their application in asymmetric transfer hydrogenation2010In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 21, no 6, p. 679-687Article in journal (Refereed)
    Abstract [en]

    The use of the tetrahydroisoquinoline scaffold is well documented in biologically active compounds. However, reports of the utilisation of tetrahydroisoquinoline compounds in asymmetric catalysis are limited. The synthesis of novel diamine ligands possessing the tetrahydroisoquinoline (tetrahydroisoquinoline) backbone and evaluation of their activity in the asymmetric transfer hydrogenation of acetophenone are presented. The diamine ligands in conjunction with i-PrOH as the hydrogen source and [RhCl2(Cp*)](2) as the metal precursor proved to be the most effective of the tetrahydroisoquinoline derivatives for this catalytic system. Water was found to have a profound influence on the enantioselectivity of the reaction. Optimisation of the amount water, i-PrOH and catalytic loading content rendered the best result of 70% enantioselectivity for the (S)-1-phenylethanol isomer product.

  • 8.
    Verendel, J Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Zhou, Taigang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Li, Jia-Qi
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Paptchikhine, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Lebedev, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Highly Flexible Synthesis of Chiral Azacycles via Iridium-Catalyzed Hydrogenation2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 26, p. 8880-8881Article in journal (Refereed)
    Abstract [en]

    A range of saturated chiral azacycles has been prepared in high yield and with high selectivity from simple starting materials. A modular approach with ring-closing metathesis as a key step was used to produce a number of five-, six-, and seven-membered cyclic alkenes. Asymmetric hydrogenation catalyzed by N,P-ligated iridium complexes gave saturated azacycles in high optical purity. This methodology was demonstrated in the synthesis of a pharmaceutical precursor.

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