Nickel-catalyzed intermolecular [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate and alkynes

The [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate (1a) and terminal alkynes (2) proceeded smoothly in the presence of 10 mol % "Ni(PPh3)2", which was prepared in situ from Ni(cod)2 and PPh3. The high reactivity of 1a, which was induced by the introduction of an electron-withdrawing group, is very important for the progress of this reaction. The cycloheptadiene derivatives were synthesized in highly selective manner in good yields.     

Palladium(II)-catalyzed sequential hydroxylation-carboxylation of biphenyl using formic acid as a carbonyl source

[reaction: see text] A simultaneous hydroxylation-carboxylation of biphenyl occurred to give 4'-hydroxy-4-biphenylcarboxylic acid, which has wide potential application as a polyester monomer.     

The first bowl-shaped stable neutral radical with a corannulene system: synthesis and characterization of the electronic structure

[structure: see text] A bowl-shaped neutral radical with a corannulene system has been designed and synthesized for the first time as a stable solid in air. An unequivocal characterization of the electronic properties of the radical shows that an appreciable amount of spin delocalization extends onto the corannulene unit's curved surface.     

Coexistence of solvated electrons and solvent valence anions in negatively charged acetonitrile clusters, (CH3CN)-n(n=10-100)

Anion photoelectron spectroscopy of acetonitrile cluster anions, (CH3CN)(-)(n) (n=10-100), successfully demonstrates the competitive coexistence of two different anionic species: a solvated electron and a solvent-bound valence anion. The distinctly different nature of these anions is revealed by hole-burning-type photoelectron spectroscopy and relative photodetachment cross section measurements. This unusual coexistence is attributed to the closely lying nature of their anionic states at just the number of solvent molecules sufficient to almost complete the first solvation layer.     

Two new tetranor-cycloartane glycosides from cimicifuga rhizome

Two new tetranor-cycloartane glycosides (1, 2) were isolated from Cimicifuga Rhizome. Their structures were determined by spectroscopic analysis. These compounds suggested the existence of a biogenetic pathway into C-23 lactone-type cycloartane glycosides.     

One-pot alpha-glycosylation method using Appel agents in N,N-dimethylformamide

[reaction: see text] A concept for the development of practical glycosylation is presented and demonstrated by one-pot alpha-glycosylation applying Appel agents for 2-O-benzyl-1-OH hexoses in DMF. The reaction, in situ giving the equilibrium of glycosyl bromides and more reactive O-glycoside intermediates, accomplishes a near-quantitative alpha-glycosylation removing the water molecules.     

Finite Modules of Finite Injective Dimension Over a Noetherian Algebra

Let R be a commutative Noetherian ring. Let P(R) (respectively,I(R)) be the category of all finite R-modules of finite projective(respectively, injective) dimension. Sharp [9] constructed acategory equivalence between I(R) and P(R) for certain Cohen–Macaulaylocal rings R. Thus many properties about finite modules offinite projective dimension can be connected with those of finiteinjective dimension through this equivalence.     

Study of Si(0 0 1)4 × 2-Ga structure by scanning tunneling microscopy and ab initio calculation

We have studied Si(0 0 1)-Ga surface structures formed at Ga coverages of slightly above 0.50 monolayer (ML) at 250 °C by scanning tunneling microscopy (STM). 4 × 2-, 5 × 2-, and 6 × 2-Ga structures were observed in a local area on the surface. The 4 × 2-Ga structure consists of three protrusions, as observed in filled- and empty-state STM images. The characters of these structures are clearly different from those of other Si(0 0 1)-Ga structures. We also performed an ab initio calculation of the energetics for several possible models for the 4 × 2-Ga structure, and clarified that the three-orthogonal-Ga-dimer model is the most stable. Also, the results of comparing the simulated STM images and observation images at various bias voltages indicate that this structural model is the most favorable.