Δ-Aryl/heteroaryl substituted heterocycles via sequential Pd-catalysed termolecular cascade/ring closing metathesis (RCM)

A novel sequential Pd-catalysed termolecular allenylation cascade/Ru catalysed RCM process affords a diverse range of Δ³-aryl/heteroaryl substituted five-seven membered nitrogen and oxygen heterocycles. Further elaboration, via 1,3-dipolar cycloaddition, in selected cases, afforded fused heterocyclic ring systems.     

Bioinspired Synthesis of Pulvinic Acids Including Xerocomic Acid and Fluorescence Properties of Bis-lactone Intermediates

A set of representative pulvinic acids were synthesised using a bioinspired strategy. Terphenyl-quinones (polyporic acid scaffold) were prepared via sequential Suzuki-Miyaura couplings allowing access to unsymmetrically substituted derivatives in a one-pot protocol. Subjected to the action of acetic anhydride and DMSO, quinones were converted into bis-lactone intermediates. Methanolysis and deprotection achieved the total syntheses of the corresponding pulvinic acids. Following this general strategy, symmetrical pulvinic, atromentic, variegatic acids and unsymmetrical congener pinastric, iso-pinastric, xerocomic and iso-xerocomic acids were prepared in fair yields. Fluorescence properties were observed for the bis-lactone intermediates and, as a complement to this synthetic work, optical properties were measured, and fluorescence quantum yields were determined for the bis-lactone pigments.     

Enhanced spontaneous emission from InAs/GaAs quantum dots in pillar microcavities emitting at telecom wavelengths

Optical properties of InAs/GaAs quantum dots in micropillar cavities emitting at 1.3 microm are studied by time-resolved microphotoluminescence. The Purcell effect is observed with an enhancement of the decay rate by a factor of two for quantum dots in resonance with the cavity mode.     

Investigation of DNA condensing properties of amphiphilic triblock cationic polymers by atomic force microscopy

Introduction of nucleic acids into cells is an important biotechnology research field which also holds great promise for therapeutic applications. One of the key steps in the gene delivery process is compaction of DNA into nanometric particles. The study of DNA condensing properties of three linear cationic triblock copolymers poly(ethylenimine-b-propylene glycol-b-ethylenimine), namely, LPEI(50)-PPG(36)-LPEI(50), LPEI(19)-PPG(36)-LPEI(19), and LPEI(14)-PPG(68)-LPEI(14), indicates that proper DNA condensation is driven by both the charge and the size of the respective cationic hydrophilic linear polyethylenimine (LPEI) and neutral hydrophobic poly(propylene glycol) (PPG) parts. Atomic force microscopy was used to investigate the interactions of the triblock copolymers with plasmid DNA at the single molecule level and to enlighten the mechanism involved in DNA condensation.     

Access to polyfunctionalized diquinanes, hydrindanes, and decalines via TiCl4 promoted Michael-aldol and Baylis-Hillman reactions

The addition of 0.5 equiv of TiCl(4) to (cyclo)alkanones tethered to α,β-unsaturated ketones afforded polyfunctionalized diquinanes, hydrindanes, and decalines. These products, resulting from a Michael-aldol or a Baylis-Hillman reaction, can be obtained with high or total diastereoselectivity in moderate to high yields. These scaffolds represent interesting building blocks for the synthesis of complex natural products.     

Unexpected isolation,and structural characterization,of a beta-hydrogen-containing sigma-alkylpalladium halide complex in the course of an intramolecular heck reaction. synthesis of polycyclic isoquinoline derivatives

The isolation of a stable beta-hydrogen-containing R-PdLn-X complex (R = alkyl; X = halide) issued from a Heck reaction is reported together with some aspects of its reactivity.     

ChemInform Abstract: Structural and Vibrational Study of [Mo7O24]6‐ and [W7O24]6‐.

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