Traceless rhodium-catalyzed hydroacylation using alkyl aldehydes: the enantioselective synthesis of β-aryl ketones

A one-pot three-step sequence involving Rh-catalyzed alkene hydroacylation, sulfide elimination and Rh-catalyzed aryl boronic acid conjugate addition, delivers products of traceless chelation-controlled hydroacylation employing alkyl aldehydes. The stereodefined β-aryl ketones are obtained in good yields with excellent control of enantioselectivity. Good variation of all three reaction components is possible

Traceless rhodium-catalyzed hydroacylation using alkyl aldehydes: the enantioselective synthesis of β-aryl ketones

A one-pot three-step sequence involving Rh-catalyzed alkene hydroacylation, sulfide elimination and Rh-catalyzed aryl boronic acid conjugate addition, delivers products of traceless chelation-controlled hydroacylation employing alkyl aldehydes. The stereodefined β-aryl ketones are obtained in good yields with excellent control of enantioselectivity. Good variation of all three reaction components is possible

Two-component assembly of thiochroman-4-ones and tet-rahydrothiopyran-4-ones using a rhodium-catalyzed alkyne hydroacylation/thio-conjugate-addition sequence

β’-Thio-substituted-enones, assembled from the combination of β-tert-butylthio-substituted aldehydes and alkynes, using rhodium-catalysis, are shown to smoothly undergo in-situ intramolecular S-conjugate addition to deliver a range of S-heterocycles in a one-pot process. Aryl, alkenyl and alkyl aldehydes can all be employed, to provide thiochroman-4-ones, hexahydro-4H-thiochromen-4-ones and tetrahydrothiopyran-4-ones, respectively. A variety of in-situ oxidations are also performed, allowing access to S,S-dioxide derivatives, as well as unsaturated variants

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing

The biology and ecology of lotic nematodes

Traunspurger W. The biology and ecology of lotic nematodes. FRESHWATER BIOLOGY. 2000;44(1):29-45.1. Morphological structures for identifying freshwater nematodes, e.g. buccal cavity, sensory receptors, oesophagus, reproductive organs and tail are described. 2. Most freshwater nematodes belong to the Adenophorea and are characterised by the presence of setae, adhesive glands and conspicuous amphids. 3. Methods for collecting nematodes from the sediments of running water (e.g. corer, pumps), within plants and aufwuchs are listed. Methods for fixation, extracting and preparing nematodes for identification are described. 4. Life history parameters (e.g. generation time, eggs per female) are not available for lotic nematodes but are summarised for free-living nematodes in soil, lakes and seas. Field studies indicate that, in contrast to laboratory experiments with nematode cultures, many species will have a generation time of several months. 5. Abundance and species diversity of nematodes of lotic habitats are provided; more than 100 nematode species inhabit lotic habitats and densities can reach 230 individuals per ml. 6. Links between meiobenthic nematodes and the micro- and macrobenthos are unclear at present. Evidence such as the increased bacterial activity due to nematode grazing suggests that such interactions may be significant