Allylic Oxidation of Alkenes Catalyzed by a Copper−Aluminum Mixed Oxide

A strategy for the allylic oxidation of cyclic alkenes with a copper−aluminum mixed oxide as catalyst is presented. The reaction involves the treatment of an alkene with a carboxylic acid employing tert-butyl hydroperoxide as the oxidant. In all cases, the corresponding allylic esters are obtained. When L-proline is employed, the allylic alcohol or ketone is obtained. The oxidation of cyclohexene and valencene has been optimized by design of experiments (DoE) statistical methodology

Acyloxylation of Cyclic Enones: Synthesis of Densely Oxygenated Guaianolides

The α′-acyloxylation of cyclic enones with linear carboxylic acids is described. The reaction is promoted by KMnO4 in the presence of a carboxylic acid and its corresponding carboxylic anhydride. The optimization of the reaction has been carried out using the statistical methodology known as design of experiments. The optimized reaction conditions have been evaluated in terms of substrate scope and compatibility with different functional groups. The methodology has been applied to the synthesis of densely oxygenated guaianes and guaianolides

Geotourism, iconic landforms and island-style speciation patterns in National Parks of East Africa:

Many of the national parks in East Africa are equally as famous for their iconic landforms as they are for their diversity and concentrations of fauna and flora. The newly formed Ngorongoro-Lengai Geopark in northern Tanzania is the first geopark to be established in the region, but there is remarkable potential for geotourism in the majority of the national parks. The most spectacular landforms have been shaped by the East African Rift System. Formation of the two major rifts in the region, the Albertine Rift (or western branch) and the Gregory Rift (or eastern branch), was accompanied, or in some cases preceded, by extensive alkaline volcanism. The rifting and volcanism are primarily Late Cenozoic phenomenon that dissected and overprinted the older regional plateaus. Rifting impacted the regional drainage and captured major rivers, including the Victoria Nile

I always seem to get the Swanee Blues

(Published By Al. Piantadosi

Photocatalytic Reduction of CO₂ with Re-Pyridyl-NHCs

A series of Re­(I) pyridyl N-heterocyclic carbene (NHC) complexes have been synthesized and examined in the photocatalytic reduction of CO₂ using a simulated solar spectrum. The catalysts were characterized through NMR, UV–vis, cyclic voltammetry under nitrogen, and cyclic voltammetry under carbon dioxide. The complexes were compared directly with a known benchmark catalyst, Re­(bpy) (CO)₃Br. An electron-deficient NHC substituent (PhCF₃) was found to promote catalytic activity when compared with electron-neutral and -rich substituents. Re­(PyNHC-PhCF₃) (CO)₃Br was found to exceed the CO production of the benchmark Re­(bpy) (CO)₃Br catalyst (51 vs 33 TON) in the presence of electron donor <b>BIH</b> and photosensitizer <i>fac</i>-Ir­(ppy)₃. Importantly, Re­(PyNHC-PhCF₃) (CO)₃Br was found to function without a photosensitizer (32 TON) at substantially higher turnovers than the benchmark catalyst Re­(bpy) (CO)₃Br (14 TON) under a solar simulated spectrum

A low recombination rate indolizine sensitizer for dye-sensitized solar cells

A sensitizer incorporating a heavily alkylated surface blocking indolizine donor exhibits excellent light absorption and diminished recombination rates in dye-sensitized solar cells (DSCs). DSC device efficiencies (up to 8%) using either I-/I-3(-) or Co(bpy)(3)(2+/3+) redox shuttles were obtained, which compare favourably to the known excellent surface coverage co-sensitization dye, D35