Stereochemistry of pteriatoxins A, B, and C

The C34 and C2' stereochemistry of pteriatoxins A-C has been established. The availability of all the stereoisomers via total synthesis has played an indispensable role.     

Theoretical and experimental guideline of optimum design of defect-inspection apparatus for transparent material using phase-shift illumination approach

Optical Review - Machine vision system has great significance for the automatic inspection to enhance unclear defects. For the purpose of the improvement of the recognition accuracy in the...     

Synthesis of alcohols from m-fluorophenylsulfones and dialkylboranes: application to the C14-C35 building block of E7389

The reaction of m-fluorophenylsulfone anions with dialkylboranes, followed by alkaline hydroperoxide oxidation, yields alcohols in high yields. Optimization of the process, scope and limitation, and application to the synthesis of one of the C14-C35 building blocks of E7389, a right half analogue of halichondrin B, are reported.     

Tuning the size of supramolecular M4L4 tetrahedra by ligand connectivity

Triangular triscatechol ligands are prepared in facile reaction sequences. The catechol units are either bound to the triangular backbone through their 3- or 4-position. With titanium(IV) ions, the ligands form metallosupramolecular M(4)L(4) tetrahedra which are characterized by ESI MS and proton NMR. Quantum-chemical calculations reveal that connectivity at the catechol in the 3-position results in highly condensed structures while attachment in the 4-position affords container molecules providing huge internal cavities.     

On Ni catalysts for catalytic, asymmetric Ni/Cr-mediated coupling reactions

The importance of the Ni catalyst in achieving catalytic asymmetric Ni/Cr-mediated coupling reactions effectively is demonstrated. Six phenanthroline-NiCl(2) complexes 1a-c and 2a-c and five types of alkenyl iodides A-E were chosen for the study, thereby demonstrating that these Ni catalysts display a wide range of overall reactivity profiles in terms of the degree of asymmetric induction, geometrical isomerization, and coupling rate. For three types of alkenyl iodides A-C, a satisfactory Ni catalyst(s) was found within 1a-c and 2a-c. For disubstituted (Z)-alkenyl iodide D, 2c was identified as an acceptable Ni catalyst in terms of the absence of Z → E isomerization and the degree of asymmetric induction but not in terms of the coupling rate. Two phosphine-based Ni catalysts, [(Me)(3)P](2)·NiCl(2) and [(cy)(3)P](2)·NiCl(2), were found to meet all three criteria for D. The bond-forming reaction at the C16-C17 position of palytoxin was used to demonstrate the usefulness of the Ni catalysts thus identified.     

Timing matters in foreign exchange markets

We show using nonlinear time series analysis that the timing of trades in foreign exchange markets has significant information. We apply a set of methods for analyzing point process data developed in neuroscience and nonlinear science. Our results imply that foreign exchange markets might be chaotic and have short-term predictability.     

Ruthenium-catalyzed glycine-selective oxidative backbone modification of peptides

The reaction of N,C-protected peptides containing glycine residues with peracetic acid in the presence of a ruthenium catalyst gives -ketoamides derived from the oxidation at the C position of the glycine residues selectively.     

The preparation of 1,4-dicarbonyl compounds by photoreaction of ketones in the presence of oxidants

Phenyl alkyl ketones were photo-irradiated in the presence of Cr(VI) or Mn(VII) oxidants to yield 1,4-dicarbonyl compounds regiospecifically while 2-octanone gave a regioisomeric mixture of 2,5-, 2,6-, and 2,7-octadiones.