Synthesis of thiophene/phenylene co‐oligomers. I. Phenyl‐capped oligothiophenes

We report the synthesis of phenyl‐capped oligothiophenes via improved synthetic schemes. These schemes are based on the Grignard coupling reaction and enable us to obtain the target compounds at high yields. The resulting materials have been fully characterized through nmr and ir spectroscopies. The ir analysis is particularly useful in characterizing the materials of higher molecular weight, since those materials are difficult to dissolve in organic solvent. We also show an improvement on preparation of halogenated (oligo)thiophenes that are used as intermediates for synthesizing the target compounds. An alternative synthetic route to the phenyl‐capped oligothiophenes that utilizes the Suzuki coupling reaction is presented as well.     

Polyion complex stabilized palladium nanoparticles for Suzuki and Heck reaction in water

Palladium nanoparticles stabilized by a polyion complex composed of poly{4-chloromethylstyrene-co-(4-vinylbenzyl) tributylammonium chloride} and poly(acrylic acid) were easily recovered by filtration after pH treatment. The polyion complex stabilized palladium nanoparticles have high catalytic activity for the Suzuki and Heck reactions in water.     

Behavioral effects of ketamine and toxic interactions with psychostimulants

Background  

The anesthetic drug ketamine (KT) has been reported to be an abused drug and fatal cases have been observed in polydrug users. In the present study, considering the possibility of KT-enhanced toxic effects of other drugs, and KT-induced promotion of an overdose without making the subject aware of the danger due to the attenuation of several painful subjective symptoms, the intraperitoneal (i.p.) KT-induced alterations in behaviors and toxic interactions with popular co-abused drugs, the psychostimulants cocaine (COC) and methamphetamine (MA), were examined in ICR mice.     

meso‐Dibenzoporphycene has a Large Bathochromic Shift and a Porphycene Framework with an Unusual cis Tautomeric Form

meso‐Monobenzoporphycene (mMBPc) and meso‐dibenzoporphycene (mDBPc), in which one or two benzene moieties are fused at ethylene‐bridged positions (meso‐positions) of porphycene, were prepared in an effort to further delocalize the π‐electrons within the porphycene molecule. mMBPc and mDBPc were fully characterized by mass spectrometry, ¹H and ¹³C NMR spectroscopy, and X‐ray crystallography. The longest‐wavelength Q‐bands of mMBPc and mDBPc are red‐shifted by 92 nm and 418 nm, respectively, compared to that of the unsubstituted porphycene (Pc). Electrochemical measurements indicate that the HOMO is destabilized and the LUMO is stabilized by the fused benzene moieties at the meso positions. Furthermore, both XPS and theoretical studies support the presence of a cis tautomeric form in the ground state of mDBPc, despite the fact that essentially all known porphycene derivatives adopt the trans tautomeric form.     

A probable hydrogen-bonded Meisenheimer complex: an unusually high S(N)Ar reactivity of nitroaniline derivatives with hydroxide ion in aqueous media

Observations show that nitroanilines exhibit an unusually high S(N)Ar reactivity with OH(-) in aqueous media in reactions that produce nitrophenols. S(N)Ar reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH(2) group far surpasses that of Cl under these conditions. An essential feature of S(N)Ar reactions of nitroanilines is probably that the NH(2) leaving group participates in a hydrogen-bonding interaction with H(2)O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH(-), and H(2)O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S(N)Ar reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.