Kuan-Jen Su

University of Vienna, Wien, Vienna, Austria

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Publications (5)19.2 Total impact

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    ABSTRACT: Foiled carbene structures comprising strong stabilizing interactions between the divalent carbon and the intramolecular double bond have been located by DFT calculations. These tetracyclic species bearing fused five-membered rings impeding intramolecular rearrangements are theoretically predicted to lie in a deep potential energy well. A suitable dibromocyclopropane precursor for this type of foiled carbene has been prepared in 12 steps. Its treatment with methyllithium led to the isolation of a product of a formal carbene dimerization, a bicyclopropylidene.
    No preview · Article · Aug 2011 · The Journal of Organic Chemistry
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    ABSTRACT: Tetravinylbenzene 4 was prepared in nearly quantitative yield from commercially available tetrabromobenzene; the improved, one-step procedure now employs Suzuki-Miyaura cross-coupling conditions. Intermolecular cyclopropanation of 4 with dibromocarbene gave a series of gem-dibromide adducts. Intramolecular cyclopropanation of monoadduct 5, putatively by its methyllithium-generated cyclopropylidene(oid), produced compound 11, which features a highly distorted spiropentane having a C-C-C bond angle of 163.5°. The stability of the reported spiropentanes was investigated using DFT calculations.
    No preview · Article · Oct 2010 · The Journal of Organic Chemistry
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    ABSTRACT: Two achiral diazirines 1a and 1b have been encapsulated in the inherently chiral cavity of a-cyclodextrin (6-Cy), beta-cyclodextrin (7-Cy) and permethylated beta-cyclodextrin (TRIMEB) and photolyzed. Because of supramolecular photochirogenesis the generated carbenes afford intramolecular C-H insertion products not as a racemate but one enantiomer is slightly favored. With 1a@(6-Cy)(2) the ee of product 7a is doubled. To the best of our knowledge for the first time for carbene reactions, products are imprinted, though modestly, with handedness derived from Cys. The reaction of 1b is highly dependent on the molecular reactor used for inclusion. Whereas 7-Cy is very efficient for favoring dimerization through azine formation, the use of TRIMEB permits exclusive formation of intramolecular insertion product 7b. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
    No preview · Article · Dec 2009 · European Journal of Organic Chemistry
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    ABSTRACT: The molecule of the title compound, C(10)H(6)N(24), lies on a crystallographic inversion centre located in the middle of the benzene ring. Steric overcrowding by the bulky N(3) groups is avoided by the tendency of four azide entities to be arranged parallel to the benzene ring and the other four azide groups to be arranged alternately above and below the benzene plane in a skeletal C(i) symmetry. The compound is of interest for high-energy research and as a precursor for the synthesis of carbon nanotubes, nanospheres or high-nitrogen carbon nitrides with great potential for biological and technological applications.
    Full-text · Article · Jun 2009 · Acta Crystallographica Section C Crystal Structure Communications
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    ABSTRACT: [reaction: see text] A reinvestigation of the thermolysis of 4,4-dibromotetracyclo[,7).0(3,5)]undec-9-ene (2) affords diene 8 with a completely rearranged hydrocarbon skeleton via the isolable intermediate 4, along with cyclopentadiene and bromobenzene. DFT calculations show that the novel tandem retro-Diels-Alder-Diels-Alder reaction with role reversal is slightly less favored than the overall single-step Cope rearrangement.
    No preview · Article · Feb 2007 · Organic Letters