Highly selective oxidative cross‐coupling polymerization with copper(I)‐bisoxazoline catalysts

The asymmetric oxidative coupling polymerization of methyl 6,6′‐dihydroxy‐2,2′‐binaphthalene‐7‐carboxylate with the copper‐diamine catalysts under an O₂ atmosphere was carried out. As is the case with the CuCl‐2,2′‐(S)‐isopropylidenbis(4‐phenyl‐2‐oxazoline) [(S)IPhO] catalyst, a polymer with a high cross‐coupling selectivity of 96% was obtained in 71% yield, whose THF‐soluble part had a number‐average molecular weight of 4.5 × 10³. To estimate the enantioselectivity with respect to the cross‐coupling linkage in the obtained polymer, the model asymmetric oxidative cross‐coupling reaction with CuCl‐(S)IPhO was also conducted, and the products showed a 94% cross‐coupling selectivity and enantioselectivity of 31% ee (S). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6287–6294, 2005     

Software for the data analysis of the arrival‐timing monitor at SACLA

X‐ray free‐electron laser (XFEL) pulses from SPring‐8 Ångstrom Compact free‐electron LAser (SACLA) with a temporal duration of <10 fs have provided a variety of benefits in scientific research. In a previous study, an arrival‐timing monitor was developed to improve the temporal resolution in pump–probe experiments at beamline 3 by rearranging data in the order of the arrival‐timing jitter between the XFEL and the synchronized optical laser pulses. This paper presents Timing Monitor Analyzer (TMA), a software package by which users can conveniently obtain arrival‐timing data in the analysis environment at SACLA. The package is composed of offline tools that pull stored data from cache storage, and online tools that pull data from a data‐handling server in semi‐real time during beam time. Users can select the most suitable tool for their purpose, and share the results through a network connection between the offline and online analysis environments.     

Cosmic-ray positron from superparticle dark matter and the PAMELA anomaly

Motivated by the anomalous positron flux recently reported by the PAMELA Collaboration, we study the cosmic-ray positron produced by the pair annihilation and the decay of superparticle dark matter. We calculate the cosmic-ray positron flux and discuss implications of the PAMELA data. We show that the positron excess observed by the PAMELA can be explained with some of the superparticle dark matter.     

Observing quantum correlation of photons in Laguerre-Gauss modes using the Gouy phase

The effect of the Gouy phase, which is one of the geometrical phases of photons, is observed through quantum correlation in Laguerre-Gaussian (LG) modes. In an experiment, the relative phase of two different LG modes of measurement basis states is manipulated via the Gouy phase, and the observed coincidence count rates agree well with theoretical predictions. This result suggests that the Gouy phase can be used as a new tool to manipulate multidimensional photonic quantum states.     

Cobalt‐Catalyzed Allylic Alkylation Enabled by Organophotoredox Catalysis

Co‐catalyzed allylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co‐catalyzed allylic alkylation using an in situ catalyst activation by organophotoredox catalysis. This noble‐metal‐free catalytic system exhibits unprecedentedly high reactivities and regioselectivities for the allylation with an allyl sulfone, for the first time, representing the unique synthetic utility of the Co‐catalyzed method compared to the related Rh‐ and Ir‐catalyzed reactions.     

Catalytic chemoselective addition of acetonitrile to enolizable aldehydes with cationic Ru complex/DBU combination

The cooperative catalysis of CpRu(PPh3)2(CH3CN)PF6 (1b) and DBU enables chemoselective nucleophilic activation of acetonitrile in the presence of base-sensitive aldehydes 2 to afford corresponding beta-hydroxynitriles in good yield.     

Synthesis, properties, and reactivity of cocaine benzoylthio ester possessing the cocaine absolute configuration

One aspect of immunopharmacotherapy for cocaine abuse involves the use of a catalytic monoclonal antibody (mAb) to degrade cocaine via hydrolysis of the benzoate ester. A cocaine benzoylthio ester analogue provides a means to implement high-throughput selection strategies to potentially isolate mAbs with high activity. The required analogue was synthesized starting from (-)-cocaine hydrochloride and possessed the cocaine absolute configuration. Key points in the preparation were the introduction of the sulfur atom at C-3 via a bromomagnesium thiolate addition to the exo face of anhydroecgonine, separation of C-2 diastereomers, recycling of a C-2 thio ester byproduct, and formation of the necessary C-2 methyl and C-3 benzoylthio esters. Effects resulting from the lower electronegativity and greater hydrophobicity of sulfur compared to oxygen were observed. These characteristics could result in interesting drug properties. Furthermore, the analogue was found to be a substrate for catalytic mAbs that hydrolyze cocaine as monitored by HPLC and also spectrophotometry by coupling cleavage of the benzoylthio ester to the disulfide exchange with Ellman's reagent. Screening antibody libraries with the new cocaine analogue using the spectroscopic assay provides an avenue for the high-throughput identification of catalysts that efficiently breakdown cocaine.     

Highly accelerating effect of lewis acids on ruthenium(II)-catalyzed radical addition reactions

The intramolecular ruthenium(II)-catalyzed radical addition of the trichloroacetyl pendant group to the 2-oxazolone skeleton is greatly enhanced in the presence of catalytic Lewis acids including rare earth metal triflates, thus providing a convenient route to a highly potential chiral synthon for vic-amino alcohols.     

UCS1025A and B,new antitumor antibiotics from the fungus Acremonium species

[structure: see text] UCS1025A and B, novel pentacyclic polyketides with an unprecedented furopyrrolizidine skeleton, were isolated from the fungus Acremonium sp. KY4917. The structures and stereochemistry were elucidated by a combination of two-dimensional NMR and X-ray crystallographic analysis. UCS1025A showed unique chemical equilibria involving three tautomeric isomers and exhibited antimicrobial activity and antiproliferative activity against human tumor cell lines.