Browsing by Author "Su, Hong"
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- ItemOpen Access[1,2-Bis(diphenylphosphino)ethane]-diiodidoplatinum(II) dichloromethane disolvate(2007) Sivaramakrishna, Akella; Su, Hong; Moss, John RIn the title compound, [PtI2(C26H24P2)]·2CH2Cl2, the PtI2(dppe) [dppe = 1,2-bis(diphenylphosphino)ethane] molecules possess twofold rotation symmetry. The Pt coordination displays a square-planar arrangement, with the sum of the angles around the Pt atom being 360.01 (2)°. The Pt-I distance is 2.6484 (5) Å. In the crystal structure, intermolecular C-H...I contacts link the PtI2(dppe) molecules into rows along the c axis, with a C...I distance of 3.873 (5) Å.
- ItemOpen Access1,7-Dimethylpentacyclo[5.4.0.02,6.-03,10.05,9]undecane-8,11-dione(International Union of Crystallography, 2010) Chakka, Sai Kumar; Onajole, Oluseye K; Govender, Thavendran; Maguire, Glenn E M; Su, Hong; Kruger, Hendrik GThe structure of the title compound, C13H14O2, a pentacycloundecane cage derivative, exhibits unusual Csp3 —Csp3 singlebond lengths ranging from 1.505 (3) to 1.607 (2) A˚ and strained bond angles as small as 88.7 (1) and as large as 121.0 (2). In this meso compound, an internal non-crystallographic mirror plane exists, bisecting the molecule. In the crystal, weak C—HO hydrogen bonds link the molecules into an infinite spiral about a twofold screw axis along the [100] direction.
- ItemOpen AccessInclusion compounds : structure, reactivity and selectivity(2002) Su, Hong; Nassimbeni, Luigi RThis thesis is concerned with structure, thermodynamic and kinetic aspects of a variety of inclusion compounds which contain small organic guests. The host compounds studied are alkaline-earth metal salts of O,O’-dibenzoyl-(2R, 3R)-tartraric acid (magnesium, calcium and strontium), 1,1’-bis-(4-hydroxyphenyl)cyclohexane (DHPC) and 2,2’-dihydroxy-1,1’-binaphthyl (BINAP). The alkaline-earth metal salts form coordination complexes with 2-methoxyethanol, water or ethanol and the guests act as a part of the coordination sphere of the metal ions. The diol host DHPC preferably forms layer type inclusion compounds with the isomers of picoline, lutidine and xylidine, as well as a number of selected solvents including 1,4-dioxane, DMSO, morpholine, THF and acetone, preferably in channel type inclusion modes. In the latter two classes of inclusion compounds the inclusion is facilitated by the formation of hydrogen bonds from the host hydroxyl moieties to the guests.
- ItemOpen AccessNovel tetracyclic structures from the synthesis of thiolactone-isatin hybrids(2010) Chibale, Kelly; Su, Hong; Hans, Renate HazelA simple and straightforward synthetic approach to potential anti-infective thiolactone-isatin hybrids led to the discovery of novel tetracyclic compounds which bear a macrocylic motif containing an unusual bridged amide bond.
- ItemOpen AccessStructure and decomposition of diol inclusion compounds(1998) Su, Hong; Coetzee, AnitaThe inclusion properties of the host, trans-9, 10-dihydroxy-9, 10-diphenyl-9,10- dihydroanthracene, with various guest molecules, namely cyclohexanone, 2- methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone, were investigated. The host to guest ratios were determined by programmed temperature thermogravimetry. Two of the four molecular structures were elucidated using single crystal X-ray diffraction. All the inclusion compounds were also characterised by differential scanning calorimetry, hotstage microscopy and Xray powder diffraction. The kinetics of decomposition of the inclusion compound containing the guest cyclohexanone were studied using different experimental techniques under isothermal conditions: these were the quartz microbalance, the levitating balance and isothermal thermogravimetry. The kinetics of decomposition of the other three compounds were studied by means of isothermal thermogravimetry. The Arrhenius parameters determined showed a compensation effect between the activation energies and pre-exponential factors. Competition experiments were performed to determine the selectivity of the host for the four guest substances.
- ItemOpen Accesstrans-Bromohydridobis-(triphenylphosphine)platinum(II)(2007) Sivaramakrishna, Akella; Su, Hong; Moss, John RThe title compound, [PtBrH(C18H15P)2], has a square-planar environment around the Pt atom, with the hydride and bromide ligands being exactly collinear with Pt since they all lie on a crystallographic twofold rotation axis, and with mutually trans triphenylphosphine ligands with a P-Pt-P bond angle that is slightly bent towards the hydride [P-Pt-P = 170.81 (5)°]. The Pt-H distance (1.610 Å) is in good agreement with those found in structures determined by neutron diffraction.
- ItemOpen AccessVinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis(Biomed Central, 2007) Hunter, Roger; Rees-Jones, Sophie; Su, HongBACKGROUND:The diastereoselectivity of a vinylogous Mukaiyama aldol reaction of a series of N-substituted 4-oxy-2-trimethylsilyloxypyrroles with a tartrate-based aldehyde has been explored as a model reaction for castanospermine synthesis. RESULTS: The study has revealed that the reaction is sensitive to the nature of the combination of N- and 4-oxy substituents. With a N-PMB or N-Bn and 4-methoxy combination, the reaction generates an aldol adduct with the correct absolute configurations for C-8 and C-8a of the indolizidine alkaloid castanospermine. The adduct was transformed to an indolizidine, whose ketal could not be transformed appropriately for the target alkaloid. CONCLUSION: The first successful diastereoselective Mukaiyama aldol strategy for the C-8 and C-8a stereogenic centres of castanospermine is presented using silyloxypyrrole chemistry. The results suggest that a full enantioselective synthesis can be realized provided that C-1 functionalisation is accomplished early in the synthesis, post-coupling.