Gold nanoparticles supported on titania catalyse, even at a ppm loading level, the quantitative reduction of nitroarenes into anilines and nitroalkanes into alkylhydroxylamines by the ammonia· borane complex. No dehalohalogenation was seen in the case of chloro-or bromonitroarenes, while ester, cyano, or carboxylic acid functionalities also remain intact. The nitroarene to aniline reduction pathway does not require nitrosoarenes as intermediate products.

Gold nanoparticles supported on TiO 2 (0.1−2% mol) catalyze at mild conditions the dehydrogenative addition of tethered 1,n-dihydrodisilanes, such as 1,1,3,3-tetramethyldisiloxane (1), 1,1,3,3tetraphenyldisiloxane (2),

No abstract

Photooxygenation of 2-thiophenyl-substituted furans in ethanol leads to the rapid, regiocontrolled, and quantitative synthesis of γ-hydroxybutenolides. The carbonyl group in butenolide holds the position of thiophenyl moiety in reacting furans. Decomposition of the initially formed [4 + 2] endoperoxide into products through a radical chain mechanism is proposed, as the fate of thiophenyl moiety is its transformation into ethyl phenylsulfenate (PhS-OEt) and diphenyldisulfide. Under the reaction conditions, the sulfenate is fast oxidized into the corresponding sulfinate.

(+)-Yaoshanenolide B was synthesized employing as a key step an endo- and face-selective Diels-Alder reaction between natural R-(-)-α-phellandrene and the exocyclic double bond of a 5-methylene-2(5H)-furanone. The dienophile furanone was prepared by photooxygenation of a suitably substituted 2-thiophenylfuran followed by dehydration of the resulting γ-hydroxybutenolide. Through this synthesis, the initially proposed structure for (+)-yaoshanenolide B has been revised to the 1R,2S,4R,7R,1″S diastereomer.