Free Self-decomposability and Unimodality of the Fuss–Catalan Distributions

Journal of Statistical Physics - We study properties of the Fuss–Catalan distributions $$\mu (p,r)$$, $$p\ge 1$$, $$01$$ there exists $$r_{0}(p)$$, with $$p-1     

Novel intramolecular photocyclization of α-arylthiophene derivatives

Photoirradiation of α-arylthiophene derivatives linked with an alkene moiety through a three-atom spacer gave unprecedented cyclobutene-fused perhydrothiapentalene-type compounds in high yields, but neither [2 + 2] nor [4 + 2] cycloaddition products. The reaction afforded a single diastereomer in many cases. The chemical structure and relative configuration of a typical product were unambiguously determined by X-ray crystallographic analysis.     

Ionic liquid pillar[5]arene: its ionic conductivity and solvent-free complexation with a guest

A room-temperature ionic liquid containing macrocyclic compound pillar[5]arene in its core was synthesized. The ionic liquid showed high thermal stability, moderate ionic conductivity and solvent-free complexation ability with the guest tetracyanoethylene.     

General asymmetric hydrogenation of alpha-branched aromatic ketones catalyzed by TolBINAP/DMAPEN-ruthenium(II) complex

[reaction: see text] A catalyst system consisting of RuCl2[(S)-tolbinap][(R)-dmapen] and t-C4H9OK in 2-propanol effects asymmetric hydrogenation of arylglyoxal dialkylacetals to give the alpha-hydroxy acetals in up to 98% ee. Hydrogenation of racemic alpha-amidopropiophenones under dynamic kinetic resolution predominantly gives the syn alcohols in up to 99% ee and >98% de, while the reaction of racemic bezoin methyl ether gives the anti alcohols in excellent stereoselectivity.     

Chiral ruthenabicyclic complexes: precatalysts for rapid, enantioselective, and wide-scope hydrogenation of ketones

A novel ruthenabicyclic complex with base shows excellent catalytic activity in the asymmetric hydrogenation of ketones. The turnover frequency of the hydrogenation of acetophenone reaches about 35,000 min(-1) in the best case, affording 1-phenylethanol in >99% ee. Several aliphatic and base-labile ketones are smoothly converted to the corresponding alcohols in high enantioselectivity. The catalytic cycle for this hydrogenation, in which the ruthenabicyclic structure of the catalyst is maintained, is proposed on the basis of the deuteration experiment and spectroscopic analysis data.     

Reaction of arynes with amino acid esters

An efficient route to a variety of 2-phenylindolin-3-ones from amino acid methyl esters has been developed. The reaction of amino acid methyl esters with benzyne prepared from 2-(trimethylsilyl)phenyl triflate and CsF gave 2-phenylindolin-3-ones in moderate to good yields.     

Research and development of an electron beam focusing system for a high-brightness X-ray generator

A new type of rotating anticathode X-ray generator, where an electron beam of up to 60 keV irradiates the inner surface of a U-shaped Cu anticathode, has achieved a beam brilliance of 130 kW mm(-2) (at 2.3 kW). A higher-flux electron beam is expected from simulation by optimizing the geometry of a combined-function-type magnet instead of the fringing field of the bending magnet. In order to minimize the size of the X-ray source the electron beam has been focused over a short distance by a new combined-function bending magnet, whose geometrical shape was determined by simulation using the Opera-3D, General Particle Tracer and CST-STUDIO codes. The result of the simulation clearly shows that the role of combined functions in both the bending and the steering magnets is important for focusing the beam to a small size. FWHM sizes of the beam are predicted by simulation to be 0.45 mm (horizontal) and 0.05 mm (vertical) for a 120 keV/75 mA beam, of which the effective brilliance is about 500 kW mm(-2) on the supposition of a two-dimensional Gaussian distribution. High-power tests have begun using a high-voltage 120 kV/75 mA power supply for the X-ray generator instead of 60 kV/100 mA. The beam focus size on the target will be verified in the experiments.     

Synthesis and reaction of tricyclic tetrathiins and pentathiepins: novel formation of α-disulfines

Cyclic polysulfanes containing a norbornane skeleton (tetrathiins and pentathiepins) were synthesized by two methods. One is the sulfurization of camphor hydrazone with disulfur dichloride, and the other is the reaction of thiocamphor with disulfur dichloride. The reduction of tetrathiin with LiEt₃BH gave the corresponding dithiol that further reacted with methyl iodide to afford the corresponding methyl sulfide. Reaction of tetrathiin with (Ph₃P)₂PdCl₂ or NiBr₂ resulted in the formation of the corresponding dithiolene metal complexes. Tetrathiins were stereoselectively oxidized by m-CPBA to afford the corresponding α-disulfines.     

Design of molecular catalysts for achievement of high turnover number in homogeneous hydrogenation

Development of highly active catalysts has been an important research area in synthetic chemistry, especially from a practical point of view. Herein, we focus on the homogeneous catalytic hydrogenation using well‐defined molecular catalysts and discuss recent advances in the field with regard to the turnover number for these catalysts. DOI 10.1002/tcr.201100019