Complementary heterogeneous/homogeneous protocols for the synthesis of densely functionalized benzo[d]sultams: C-C bond formation by intramolecular nucleophilic aromatic fluorine displacement

Polyfunctionalized benzo[d]sultams 7 and 8, which contain an alpha-amino acid unit, have been synthesized from the corresponding open chain (pentafluorobenzene)sulfonamides 4 by complementary solid-liquid phase transfer catalysis (SL-PTC) and homogeneous protocols. The cyclization step proceeds through the intramolecular nucleophilic displacement of an aromatic fluorine atom.     

Synthesis of enantiopure 3,6,7,8-tetrahydrochromeno[7,8-d]imidazoles via asymmetric ketone hydrogenation in the presence of RuCl2[Xyl-P-Phos][DAIPEN]

The asymmetric hydrogenation of complex heterocyclic ketones 1 in the presence of the novel catalyst RuCl₂[(S)-Xyl-P-Phos][(S)-DAIPEN] and a base afforded the corresponding alcohols 2 in good enantiomeric purity. The outcome of the reaction depended on the substitution pattern of the ketone and the stoichiometry of the base. After optimization of the reaction conditions, the pure alcohols 2a and 2b were isolated in good yield (>70%) and enantiomeric purity (>93% ee) and used as key intermediates for the synthesis of the pharmaceutically active 3,6,7,8-tetrahydrochromeno[7,8-d]imidazoles 3a and 3b.     

H2S gas interaction with Pt(II)-containing polymetallaynes of selected chain length: an XPS and EXAFS study

The interaction between gaseous H2S and the surface of several metal-containing oligomers, investigated by emission and absorption spectroscopies, is presented and discussed. The polymetallayne trans-{Cl-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]9Pt(PBu3)2Cl} and related model molecules, i.e. the binuclear transition metal dialkynyl bridged Pt(II) square planar complex trans, trans-[ClPt(PBu3)2(CC-C6H4-C6H4-CC)Pt(PBu3)2Cl], the tetranuclear linear oligomer trans-{Cl-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]3Pt(PBu3)2Cl}, the tetranuclear cyclic oligomer cis-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]4, were exposed to hydrogen sulfide and then investigated by X-ray photoelectron (XPS) and X-ray absorption (XAS) spectroscopies, in order to shed light on the gas/polymer interaction associated to the sensing properties of these materials. XPS measurements evidenced the presence of S in the polymetallayne samples exposed to H2S, and the measured S2p binding energy values correlate with H2S adsorbed by means of sulfur atoms chemically bonded to metal atoms, owing to the formation of sulfur-containing adducts. XAS data analysis suggested a square-pyramidal geometry around the transition metal with H2S in the apical position for the pentacoordinated platinum units.     

The wave equation on hyperbolic spaces

We study the dispersive properties of the wave equation associated with the shifted Laplace–Beltrami operator on real hyperbolic spaces and deduce new Strichartz estimates for a large family of admissible pairs. As an application, we obtain local well-posedness results for the nonlinear wave equation.