Productive utilization of chlorobenzene: palladium-catalyzed selective oxidation of alcohols

[reaction: see text] The palladium/ligand-catalyzed activation of chlorobenzene provides a general, efficient, and functional group friendly method for the selective oxidation of alcohols to carbonyl compounds.     

Spirocyclopropanated bicyclopropylidenes: straightforward preparation, physical properites, and chemical transformations

Perspirocyclopropanated bicyclopropylidene (6) was prepared in three steps from 7-cyclopropylidenedispiro[2.0.2.1]heptane (4) (24% overall) or, more efficiently, through dehalogenative coupling of 7,7-dibromo[3]triangulane (15) (82%). This type of reductive dimerization turned out to be successful for the synthesis of (E)- and (Z)-bis(spiropentylidene) 14 (67%) and even of the "third-generation" spirocyclopropanated bicyclopropylidene 17 (17% overall from 15). Whereas the parent bicyclopropylidene 1 dimerized at 180 degrees C to yield [4]rotane, dimerization of 6 at 130 degrees C under 10 kbar pressure occured only with opening of one three-membered ring to yield the polyspirocyclopropanated (cyclopropylidene)cyclopentane derivative 19 (34% yield), and at the elevated temperature the polyspirocyclopropanated 2-cyclopropylidene[3.2.2]propellane derivative 20 (25 % yield). Perspirocyclopropanated bicyclopropylidene 6 and the "third-generation" bicyclopropylidene 17 gave addition of bromine, hydrogen bromide, and various dihalocarbenes without rearrangement. The functionally substituted branched [7]triangulane 28 and branched dichloro-C2v-[15]triangulane 32 were used to prepare the perspirocyclopropanated [3]rotane (D3h-[10]triangulane) 49 (six steps from 6, 1.4% overall yield) and the C2v-[15]triangulane 51 (two steps from 17, 41% overall). Upon catalytic hydrogenation, the perspirocyclopropanated bicyclopropylidene 6 yielded 7,7'-bis(dispiro[2.0.2.]-heptyl) (52) and, under more forcing conditions, 1,1'-bis(2,2,3,3-tetramethylcyclopropyl) (53). The bromofluorocarbene adduct 33 of 17 reacted with butyllithium to give the unexpected polyspirocyclopropanated 1,4-di-n-butyl-2-cyclopropylidenebicyclo[2.2.0]hexane derivative 37 as the main product (55% yield) along with the expected "third-generation" perspirocyclopropanated dicyclopropylidenemethane 38 (21% yield). Mechanistic aspects of this and the other unusual reactions are discussed. The structures of all new unusual hydrocarbons were proven by X-ray crystal structure analyses, and the most interesting structural and crystal packing features are presented.     

Cocaine reward and locomotion stimulation in mice with reduced dopamine transporter expression

Background  

The dopamine transporter (DAT) plays a critical role in regulating dopamine neurotransmission. Variations in DAT or changes in basal dopaminergic tone have been shown to alter behavior and drug responses. DAT is one of the three known high affinity targets for cocaine, a powerful psychostimulant that produces reward and stimulates locomotor activity in humans and animals. We have shown that cocaine no longer produces reward in knock-in mice with a cocaine insensitive mutant DAT (DAT-CI), suggesting that cocaine inhibition of DAT is critical for its rewarding effect. However, in DAT-CI mice, the mutant DAT has significantly reduced uptake activity resulting in elevated basal dopaminergic tone, which might cause adaptive changes that alter responses to cocaine. Therefore, the objective of this study is to determine how elevated dopaminergic tone affects how mice respond to cocaine.     

trans‐1,2,3‐Tris(1‐hydroxycyclo­propyl)cyclopropane

The central three‐membered ring in the title compound, trans‐1,1′,1′′‐cyclo­propane‐1,2,3‐triyl­tris­(cyclo­propanol), C₁₂H₁₈O₃, shows pronounced asymmetry of the bond lengths, which is induced by the different orientations of the substituents. A network of hydrogen bonds links the mol­ecules into sheets.     

Use of ion chromatography with post-column reaction for the measurement of tribromide to evaluate bromate levels in drinking water

A user-friendly ion chromatography method in conjunction with a post-column reaction (PCR) achieves practical quantitation limits for the oxyhalides bromate and chlorite of 0.05 μg/l and 0.10 μg/l, respectively. This level of measurement allows for the accurate assessment of bromate contributed to finished drinking waters that have been chlorinated using sodium hypochlorite. The target sensitivity of oxyhalides in the presence of other major ion species typically found in drinking water is achieved by PCR using excess bromide under acidic conditions to form a tribromide species that is detected by ultraviolet spectrometry. The method setup involves non-hazardous materials, as opposed to other recently developed methods that employ somewhat hazardous chemicals for generating the reaction necessary for the detection of bromate at sub-μg/l levels. No pretreatment of the samples is required, other than filtration and quenching of oxidant residual.     

Eine Methode zum Nachweis und zur qualitativen Trennung von Ferrocyaniden, Ferricyaniden und Rhodaniden

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