Ruthenium-catalyzed intramolecular oxidative amination of aminoalkenes enables rapid synthesis of cyclic imines.

[RuCl2(CO)3]2/dppp is shown to be a highly effective catalyst system for the first intramolecular oxidative amination of a variety of aminoalkenes when it is used concomitantly with K2CO3 and allyl acetate in N-methylpiperidine, to give the corresponding cyclic imines and indoles in excellent yields. For example, the reaction of 2,2-diphenyl-4-pentenyl-1-amine performed in the presence of 2 mol % of [RuCl2(CO)3]2, 4 mol % of dppp, K2CO3, and allyl acetate in N-methylpiperidine at 140 degrees C for 8 h gives 4,4-diphenyl-2-methyl-1-pyrroline in quantitative (>99%) yield.     

Aerobic oxidative dehydrogenation of benzyl alcohols to benzaldehydes by using a cyclometalated ruthenium catalyst

The ruthenium(III) complex bearing phenylpyridine as a cyclometalated ligand serves as an efficient catalyst for the aerobic oxidative dehydrogenation of benzyl alcohols to the corresponding benzaldehydes under mild conditions and for the one-pot synthesis of benzonitriles from benzyl alcohols with ammonia.     

Electrochemical generation of silver acetylides from terminal alkynes with a Ag anode and integration into sequential Pd-catalysed coupling with arylboronic acids

An electro-oxidative method for generating silver acetylides from acetylenes with a Ag anode was developed. The reaction could be integrated into a Pd-catalysed electrochemical Sonogashira-type reaction. In the presence of the catalytic amount of Pd(OAc)(2) and 4-BzO-TEMPO, electro-generated silver acetylides reacted immediately with arylboronic acids to afford the corresponding coupling adducts in high yields.     

Synthesis of 2′,3′-dideoxynucleosides via C-S bond cleavage: N-glycosylation of 2,3-dideoxy-1-[(2-pyridylmethyl)thio]glycoside

N-Glycosylation of 2,3-dideoxy-1-[(2-pyridylmethyl)thio]glycosides (1a) using several activators is described. NBS-promoted glycosylation reaction utilizing either the α- or β-thiodideoxyglycoside proceeded smoothly at −78 °C to give the corresponding dideoxynucleoside in a β-selective manner, presumably through a common glycosyl donor.     

Ruthenium-catalyzed [2 + 2 + 1] cocyclization of isocyanates, alkynes, and CO enables the rapid synthesis of polysubstituted maleimides

Intermolecular [2 + 2 + 1] cocyclization of isocyanates, alkynes, and CO (1 atm) proceeded smoothly in the presence of a catalytic amount of Ru3(CO)12 (3.3 mol %) in mesitylene at 130 degrees C for 3 approximately 42 h to give a variety of polysubstituted maleimides in excellent yields with high selectivity. The reaction may involve an azaruthenacyclopentenone intermediate derived from oxidative cyclization of an isocyanate and an alkyne on an active ruthenium species.     

Reductive elimination of C6F5-C6F5 in the reaction of bis(pentafluorophenyl)palladium(II) complexes with protic acids

Reductive elimination of C6F5-C6F5 from cis-[Pd(C6F5)2L] (L = cod, bpy, and dppb) was promoted by Br?nsted acids. HNO3 is a convenient acid for the formation of C6F5-C6F5 from [Pd(C6F5)2(cod)]. The products are controlled by the auxiliary ligand.     

Electrooxidative glycosylation through C-S bond cleavage of 1-arylthio-2,3-dideoxyglycosides. Synthesis of 2',3'-dideoxynucleosides

[reaction: see text] The electrooxidative glycosylation of newly designed 1-arylthio-substituted 2,3-dideoxyglycosides is described. The halide salt-mediated electrooxidation utilizing either of the alpha- or beta-thiodideoxyglycosides proceeded smoothly at -78 degrees C to give dideoxynucleosides in a beta-selective manner, presumably through a 1-halo-substituted glycosyl donor.     

Computer Simulation of Axis-Encircling Beams Generated by an Electron Gun with a Permanent Magnet System

Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University.     

Rhodium-catalyzed rapid synthesis of substituted phenols from cyclobutenones and alkynes or alkenes via C-C bond cleavage

A novel rhodium-catalyzed synthesis of substituted phenols by the ring-opening reaction of cyclobutenones with alkynes as well as electron-deficient alkenes has been developed. Both reactions involve C-C bond cleavage of cyclobutenones, and an (η⁴-vinylketene)rhodium complex rather than a rhodacyclopentenone is considered to be a key intermediate.     

Design of a Large Orbit Gyrotron with a Permanent Magnet System

The paper presents results of numerical analysis and outlines the computer-aided design of a novel high-harmonic gyrotron with a beam of electrons gyrating along axis-encircling trajectories. The electron beam is formed by a novel electron-optical system (EOS) based on an electron gun of diode type with thermionic cathode and gradual reversal of the magnetic field. The results of numerical simulations predict satisfactory performance of the EOS and appropriate beam quality parameters. The tube design allows one to install different cavities optimized for excitation of TE_4,1 mode at the fourth harmonic of the cyclotron frequency or TE_3,1 mode at the third one. The target parameters of the device are: frequency about 112 GHz; output power near 1 kW and efficiency of several percent.