A novel approach to 2-arylated quinolines: electrocyclization of alkynyl imines via vinylidene complexes

[reaction: see text] Alkynyl imines underwent [4 + 2] electrocyclization in the presence of 20 mol % W(CO)(5)(THF) to give 2-arylated quinolines in good yields. A deuterium labeling study suggests that the reaction proceeds via a tungsten vinylidene complex.     

Production of methyltin compounds related to possible conditions in the environment

The methylation of heavy-metal compounds (e.g. mercury, lead, tin) in the environment has great significance owing to the much higher toxicity of their methyl derivatives in comparison with inorganic metal species. In this paper abiological methylation of inorganic tin is described. Ethanol, acetic acid and propionic acid abiologically methylated inorganic tin, and the highest yield of methyltin was observed in the reaction between inorganic tin(II) and ethanol. Furthermore, environmental factors for the methylation, such as pH, temperature, added ethanol, concentration of sodium chloride and photoirradiation, were investigated in this reaction. Methyltin production increased at low pH, and decreased at higher concentrations of sodium chloride. Photoirradiation accelerated the reaction rate, and a shorter wavelength showed a higher rate. Inorganic tin(II) was converted rapidly into monomethyltin, and gradually transformed into dimethyltin and trimethyltin with the course time.     

Synthesis and conformational properties of 5,7-disubstituted [3.3] Metacyclo (2,5) thiophenophane-1,12-diones

The title compounds showed unique conformational equilibria which were dependent upon the substituents in the 5,7-positions, the predominant conformers being in a $\text{syn}$ O,S,O-$\text{cis}$,$\text{cis}$ conformation with a highly deformed thiophene-2,5-dicarbonyl moiety.     

Shinjulactone C,a new quassinoid ith a 1α, 12α:5α, 13α-dicyclo-9βH-picrasane skeleton from ailanthus altissima SWINGLE

A new non-bitter quassinoid, named shinjulactone C ($\text{1}$), was isolated from the root bark of $\text{Ailanthus altissima}$ SWINGLE and shown to be 1α, 12α:5α, 13α-dicyclo-1β, 12β, 20-trihydroxy-9β$\text{H}$-picras-3-ene-2, 11, 16-trione by X-ray diffraction method.     

Cu(I)-catalyzed enantioselective [3 + 2] cycloaddition reaction of 1-alkylallenylsilane with alpha-imino ester: asymmetric synthesis of dehydroproline derivatives

[reaction: see text] The catalytic, enantioselective [3 + 2] cycloaddition reaction of 1-alkyl-substituted allenylsilanes with alpha-imino ester has been achieved by means of [Cu(MeCN)(4)]BF(4)/(R)-DM-SEGPHOS catalyst to afford silyl-substituted dehydroproline derivatives in high yields and enantioselectivities.