A novel direct synthesis of (2,2-difluorovinyl)benzenes from aromatic aldehydes

A novel catalytic approach to (2,2-difluorovinyl)benzenes has been developed. It was found that hydrazones of aromatic aldehydes generated in situ could be converted to the corresponding (2,2-difluorovinyl)benzenes by catalytic olefination reaction (COR) with dibromodifluoromethane in the presence of CuCl.     

A weight-function approach for determining watershed initial conditions for combustion waves

In many generic combustion models, one finds that a combustionwave will develop with a specific wave speed. However, thereare possible initial temperature profiles which do not evolveinto such waves, but rather die out to the ambient temperature.There can exist, in some models, a clear distinction betweenthose initial conditions that do evolve into combustion wavesand those that do not; this is sometimes referred to as thewatershed initial condition. When fuel consumption is consideredto be negligible, analytical methods can be used to obtain theexact watershed. In this paper, we consider the problem of determiningpseudo-watersheds and ascertaining the relationship betweenthese pseudo-watersheds and the exact watersheds. In the processa novel weight-function approach for infinite spatial domainsis developed.     

Reaction of CBrF2-CBrF2 with hydrazones of aromatic aldehydes: Novel efficient synthesis of fluorocontaining alkanes, alkenes and alkynes

An olefination of hydrazones of aromatic aldehydes by CBrF₂-CBrF₂ under copper catalysis was investigated. In situ prepared aldehydes hydrazones were converted to (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by reaction with CBrF₂-CBrF₂ in the presence of CuCl. Subsequent elimination of HF by sodium hydroxide resulted in stereospecific formation of fluorocontaining alkenes. Elimination proceeds stereoselectively, only Z-isomers of alkenes are formed. Elimination of two molecules of HF from (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by treatment with potassium tert-butoxide leads to formation of (bromodifluoromethyl)alkynes. As a result a simple and efficient transformation of aromatic aldehydes to range of various fluorinated alkanes, alkenes and alkynes was elaborated.     

New Synthesis of β-Iodostyrenes

A general procedure for the synthesis of -iodostyrenes is proposed. Aromatic aldehyde and ketone hydrazones are converted into the corresponding -iodostyrenes by treatment with CHI₃ in the presence of a catalytic amount of CuCl.     

A novel palladium-catalyzed arylation-dehydroaromatization reaction: synthesis of 7-aryltetralones

A new one-pot room-temperature palladium-catalyzed synthesis of 7-aryltetralones was discovered. This tandem process includes a palladium-catalyzed gamma-selective arylation of the enone 4 followed by a dehydrogenation-aromatization of the initial cross-coupling product. [reaction: see text]     

Recording long-term potentiation of synaptic transmission by three-dimensional multi-electrode arrays

Background  

Multi-electrode arrays (MEAs) have become popular tools for recording spontaneous and evoked electrical activity of excitable tissues. The majority of previous studies of synaptic transmission in brain slices employed MEAs with planar electrodes that had limited ability to detect signals coming from deeper, healthier layers of the slice. To overcome this limitation, we used three-dimensional (3D) MEAs with tip-shaped electrodes to probe plasticity of field excitatory synaptic potentials (fEPSPs) in the CA1 area of hippocampal slices of 129S5/SvEvBrd and C57BL/6J-Tyr^C-Brd mice.     

The catalytic olefination reaction of aldehydes and ketones with CBr3CF3

The new approach of catalytic olefination reaction (COR) has been used to convert aromatic and aliphatic aldehydes and ketones to 2-bromo-3,3,3-trifluoroprop-1-enes by the treatment of corresponding hydrazones with CBr₃CF₃ under copper(I) catalysis conditions. The reaction proceeds stereoselectively, the target alkenes were obtained in good yields.