Now showing 1 - 8 of 8
  • Placeholder Image
    Publication
    Organocatalytic Enantioselective Assembly of Spirooxindole-naphthopyrans through Tandem Friedel-Crafts Type/Hemiketalization
    (09-05-2016)
    Muthusamy, Subramaniam
    ;
    Prakash, Muthuraj
    ;
    Ramakrishnan, Chandrasekaran
    ;
    ;
    A new synthetic strategy to construct spirooxindole-naphthopyran scaffold has been demonstrated via Friedel-Crafts type/hemiketalization of oxindole α-ketoester with 2-naphthol. Under the established reaction condition, quaternary chiral center at C3-position of oxindole has been created with very good asymmetric induction up to 98 % for a broad range of substrates. DFT calculations, which account for the stereochemical outcome, were performed.
  • Placeholder Image
    Publication
    Construction of Polycyclic Fused Pyrrolidines with Three Contiguous Stereocenters via Michael Addition of Vinylmalononitriles to Nitrostyrenes Using l -Proline-Derived Thiourea
    (16-08-2016)
    Vishwanath, Manjunatha
    ;
    Prakash, Muthuraj
    ;
    Vinayagam, Poopathy
    ;
    The catalytic efficiency of a bifunctional chiral thiourea derived from l-proline was evaluated in the asymmetric direct vinylogous Michael reaction of α,α-dicyanoolefins to β-nitrostyrenes with an electron-releasing or electron-withdrawing substituent in various positions. The corresponding adducts were isolated in good yields, with excellent diastereo- (>99%) and enantioselectivity (up to 95%). The Michael adducts were further functionalized to achieve the synthesis of polycyclic fused pyrrolidines with three contiguous stereocenters in good enantioselectivities.
  • Placeholder Image
    Publication
    Copper(I) bromide catalyzed arylation of cyclic enamides and naphthyl-1-acetamides using diaryliodonium salts
    (05-09-2014)
    Prakash, Muthuraj
    ;
    Muthusamy, Subramaniam
    ;
    Copper(I) bromide catalyzed direct C-H arylation of cyclic enamides was achieved using diaryliodonium salts in the absence of base/additive at ambient temperature with high yields. A biologically active dihydro[a]benzocarbazole scaffold was synthesized using the established protocol. The scope of the current methodology was further extended for the synthesis of C4-, C7-aryl-substituted 1-naphthyl acetamides in good yields.
  • Placeholder Image
    Publication
    Assembly of 3-allyl-3-ethynyl-oxindole motifs via palladium(ii)-catalyzed quaternary allylation of 3-ethynyl-3-OBoc-oxindoles
    (01-01-2015)
    Kumarswamyreddy, Nandarapu
    ;
    Prakash, Muthuraj
    ;
    Jayakumar, Samydurai
    ;
    Palladium(ii)-catalyzed C3-allylation of 3-ethynyl-3-OBoc oxindole derivatives was achieved for the first time to access highly functionalized 3-allyl-3-ethynyl substituted oxindole derivatives for a broad range of substrates in very good yields (up to 94%). The synthetic applications of the allylated products were explored by synthesizing five and six membered carbocyclic spirooxindoles in moderate to very good diastereoselectivities.
  • Placeholder Image
    Publication
    Highly enantioselective synthesis of 2,3-dihydroquinazolinones through intramolecular amidation of imines
    (06-04-2012)
    Prakash, Muthuraj
    ;
    Enantioselective synthesis of 2,3-dihydroquinazolinones (DHQZs) was accomplished using readily available Sc(III)-inda-pybox as the catalyst. This is the first report on the metal catalyzed asymmetric intramolecular amidation of imines to synthesize DHQZs. © 2012 American Chemical Society.
  • Placeholder Image
    Publication
    Palladium catalyzed asymmetric allylation of 3-OBoc-Oxindoles: An efficient synthesis of 3-Allyl-3-hydroxyoxindoles
    (06-03-2015)
    Jayakumar, Samydurai
    ;
    Kumarswamyreddy, Nandarapu
    ;
    Prakash, Muthuraj
    ;
    3-Allyl-3-hydroxyoxindoles were synthesized in very good enantio- (up to 97% ee) and diastereoselectivities (dr up to 7.6:1) with contiguous quaternary and tertiary stereogenic centers by employing tartrate derived bi(oxazoline) in Pd-catalyzed allylation of 3-OBoc-oxindole. Synthetic utility of 3-allyl-3-hydroxyoxindole was demonstrated by synthesizing a highly substituted spiro(oxindole-3,2′-tetrahydrofuran) derivative in good yield and stereoselectivity.
  • Placeholder Image
    Publication
    Highly enantioselective alkylation of allyl acetates using tartrate-derived bioxazoline ligands
    (01-01-2014)
    Jayakumar, Samydurai
    ;
    Prakash, Muthuraj
    ;
    Balaraman, Kaluvu
    ;
    Tartrate-derived bioxazoline ligands, which form a five-membered chelate ring with metals, were evaluated for use in the asymmetric allylic alkylation (AAA) reactions of various symmetrical and unsymmetrical allyl acetates. Excellent enantioselectivities were achieved by using both symmetrical and unsymmetrical allyl acetates. Palladium(II)-catalyzed asymmetric allylic alkylation reactions of various symmetrical and unsymmetrical allyl acetates were achieved by using bioxazoline ligands, which were derived from tartaric acid, to give products with excellent enantioselectivity. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Placeholder Image
    Publication
    Investigation of the enantioselective synthesis of 2,3- Dihydroquinazolinones Using Sc(III)- Inda -pybox
    (15-07-2013)
    Prakash, Muthuraj
    ;
    Jayakumar, Samydurai
    ;
    Derivatives of 2,3-dihydroquinazolinones (2,3-DHQZs) are prized for their prevalent pharmaceutical applications. Although there are potential applications, methods available for the enantioselective synthesis of these valuable compounds are scarce, since the chiral aminal center is prone to racemization. We have overcome the difficulties in the catalytic enantioselective synthesis of 2,3-DHQZs using Sc(III)-inda-pybox as a catalyst, in a process with a broad substrate scope. © Georg Thieme Verlag Stuttgart. New York.