A New Synthesis of Polysubstituted Cyclopropanes

Polysubstituted cyclopropane derivatives (3a-3h) could be obtained by reaction of activate olefinic compounds (2) with the cyanophosphates (1) aldehydes (benzaldehyde, cinnamaldehyde and croton-aldehyde) in the presence of butyllithium and tetra-methylethylenediamine in tetrahydrofuran via a Michael addition followed by 1,3-elimination.     

Development of novel and efficient synthesis of group 14 element (Ge and Sn) catenates by use of samarium (II) diiodide

Group 14 element catenates such as di-, tri-, poly-germanes, and polystannanes are efficiently synthesized by use of the one-electron reducing agent SmI₂ under mild homogeneous conditions in good yields.     

Interaction of Au(III) and Pt(IV) complex ions with Fe(II) ions as a scavenging and a reducing agent: a basic study on the recovery of Au and Pt by a chemical method

In order to develop a chemical technique for the recovery of gold (Au) and platinum (Pt) in the metallic state from spent catalysts, e.g., catalysts for environmental protection and automobile and petroleum catalysts, the coprecipitation behaviors of Au(III) and Pt(IV) complex ions with Fe(OH)(2) as a scavenging and reducing agent were investigated. The Au(III) complex ions were found to be stoichiometrically and rapidly reduced to metallic Au due to electron transfer in acidic aqueous solution prior to coprecipitation with Fe(OH)(2). Conversely, Pt(IV) complex ions were reduced only after coprecipitation with Fe(OH)(2) due to electron transfer through a Pt(IV)-O-Fe(II) bond on the solid Fe(OH)(2). Using this chemical technique, Au and Pt can be selectively and effectively recovered in the metallic state.     

Phase synchronization and synchronization frequency of two-coupled van der Pol oscillators with delayed coupling

In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and the necessary conditions for phase synchronization are also achieved. Finding the vicinity of the synchronization frequency is the major advantage of the describing function method over other traditional methods. The equations obtained based on this method justify the phenomenon of the synchronization of coupled oscillators on a frequency either higher, between, or lower than the highest, in between, or lowest natural frequency of the aggregate oscillators. Several numerical examples simulate the different cases versus the various synchronization frequency delays.     

Marked differences in volume phase transitions between gel and single molecule in DNA

Volume phase transitions of a DNA gel and a single giant DNA chain caused by spermidine(3+) (SPD(3+)) were investigated. The change in volume for the single DNA (VV(0) approximately 10(-5)) was four orders of magnitude greater than that for the DNA gel ( approximately 10(-1)), while the critical SPD(3+) concentration for the gel (1.8 mM) was one order of magnitude greater than that of the single DNA (0.12-0.25 mM) at the same pH 6.86. We tried to describe mean-field theories with virial expansion, which is valid for the coil-globule transition of a single polymer chain, for the volume phase transitions to explain the reason why such marked differences appeared. Considering the degree of the ordering of Kuhn segments arising from the gel network structure together with the chain length of cross-linked polymer chains, the volume phase transitions were described and then the significant differences were reproduced quantitatively. We concluded that the network structure plays a significant role in the volume phase transition of the gel.     

Synthesis and physical properties of N-2-phenylethyl- and N-2-(3-indolyl)ethyl-5′-deoxy-5′-adenosineacetamides

The synthesis and physical properties of N-2-phenylethyl- and N-2-(3-indolyl)ethyl-5′-deoxy-5′-adenosineacetamides ( 2 and 3 ), which are stable compounds of phenylalanyl- and tryptophanyl-AMPs, are described.     

Studies on indenopyridine derivatives and related compounds. II. Stereochemistry of 1-substituted 9-phenyl-1,3,4,4a,9,9a-hexahydro-4-hydroxy-2H-indeno[2,1-b] pyridines and their acetates

Chemical and catalytical reduction of 1-methyl- or 1-benzyl-phenyl-1,3,4,9-tetrahydro-2H-indeno[2,1-b ]pyridin-4-ones (VIIa,b) afforded 1-methyl- or 1-benzyl-9-phenyl-1,3,4,4a,9,9a- hexahydro-4-hydroxy-2H-indeno[2,1-b ]pyridines (IXa,b), which gave the corresponding acetates (Xa,b) by treatment with acetic anhydride and pyridine. Based upon a detailed study of 100 MHz nmr spectra of these compounds, it was concluded that the hydroxy group of IXa,b has an axial configuration taking B/C cis stable form which has the large aromatic group equatorial with respect to the piperidine ring, whereas the acetoxy group of Xa,b is equatorial taking an unfavorable B/C cis unstable form which has the large aromatic group axial with respect to the piperidine ring.