Lanthanum immobilized on chitosan: a highly efficient heterogeneous catalyst for facile synthesis of novel (α,β‐unsaturated) β‐aminoketones

A new heterogeneous catalyst, lanthanum immobilized on chitosan, was synthesized and used for the aza‐Michael reaction of β‐enaminone under microwave irradiation. The characteristic structural features of the catalyst were determined using Fourier transform infrared spectroscopy, powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, transmission and scanning electron microscopies and inductively coupled plasma atomic emission spectroscopy. The stability of the catalyst was evaluated using thermogravimetric analysis. The use of recyclable catalyst and glycerol as solvent makes this procedure environmentally benign and economically viable. Copyright © 2016 John Wiley & Sons, Ltd.     

Efficient and Ecofriendly Protocol for Tetrahydropyranylation/Depyranylation of Alcohols in the Presence of Tin(II) Chloride Dihydrate

A mild, efficient, and solvent‐free protocol for tetrahydropyranylation of alcohols in the presence of a catalytic amount of SnCl₂ · 2H₂O is reported. Simple filtration of the reaction mixture through a short silica‐gel pad gives the pure products in excellent yields. Depyranylation can also be achieved by adding methanol under similar reaction conditions.     

Microwave-Assisted Chemoselective Regeneration of Carbonyl Compounds from Oximes by Silica Chromate/WET SiO2 Under Solvent-Free Conditions

The regeneration of carbonyl compounds from oximes were performed by using silica chromate and wet SiO ₂ (w/w 50%) under microwave irradiation and solvent-free conditions with excellent yields.     

MAGNESIUM HYDROGEN SULFATE POWDER CATALYZED STEREOSELECTIVE CONVERSION OF DIALKYL 2-(IMIDO-N -YL)-3-(TRIPHENYLPHOSPHORANYLIDENE)- BUTANEDIOATES TO ELECTRON-POOR (Z)-N -VINYLIMIDES IN SOLVENT-FREE CONDITIONS

Magnesium hydrogen sulfate powder was found to catalyze stereoselective conversion of dialkyl 2-(imido-N-yl)-3-(triphenylphosphorany-lidene)butanedioates to electron-poor (Z)-N-vinylimides in solvent-free conditions at 95°C 1 h in high conversions. Microwave also was found to catalyze the same reactions in the presence of magnesium hydrogen sulfate powder in solvent-free conditions in 3 min.     

Microwave‐Enhanced Ferrier Reaction: A Facile Synthesis of 2,3‐Unsaturated‐O‐Glycosides Under Solvent‐Free Conditions

A variety of 2,3‐unsaturated‐O‐glycosides have been prepared by the Ferrier rearrangement of acetyl protected glycals under microwave irradiation using silica gel as an acid catalyst. Environmental friendliness, high yields, and short reaction times are the key features of this method. Furthermore, the method was applicable not only to the Ferrier reaction of 3,4,6‐tri‐O‐acetyl glucal and 3,4,6‐tri‐O‐acetyl galactal but also to the Ferrier reaction of 3,4‐di‐O‐acetyl arabinal.     

Historical data learning based dynamic LSP routing for overlay IP/MPLS over WDM networks

Overlay IP/MPLS over WDM network is a promising network architecture starting to gain wide deployments recently. A desirable feature of such a network is to achieve efficient routing with limited information exchanges between the IP/MPLS and the WDM layers. This paper studies dynamic label switched path (LSP) routing in the overlay IP/MPLS over WDM networks. To enhance network performance while maintaining its simplicity, we propose to learn from the historical data of lightpath setup costs maintained by the IP-layer integrated service provider (ISP) when making routing decisions. Using a novel historical data learning scheme for logical link cost estimation, we develop a new dynamic LSP routing method named Existing Link First (ELF) algorithm. Simulation results show that the proposed algorithm significantly outperforms the existing ones under different traffic loads, with either limited or unlimited numbers of optical ports. Effects of the number of candidate routes, add/drop ratio and the amount of historical data are also evaluated.     

Une extension d'une inégalité de burkholder,davis, gundy pour les processus à α-variation bornée et applications

An increasing process associated in a natural sense with each process of bounded x-variation leads us to an extension of an inequality of Burkholder, Davis, Gundy and allows us to determine the regularity of such processes     

Three Short Stories about Hexaarylbenzene–Porphyrin Scaffolds

A feasible two‐step synthesis and characterization of a full series of hexaarylbenzene (HAB) substituted porphyrins and tetrabenzoporphyrins is presented. Key steps represent the microwave‐assisted porphyrin condensation and the statistical Diels–Alder reaction to the desired HAB‐porphyrins. Regarding their applications, they proved to be easily accessible and effective high molecular mass calibrants for (MA)LDI mass spectrometry. The free‐base and zinc(II) porphyrin systems, as well as the respective tetrabenzoporphyrins, demonstrate in solid state experiments strong red‐ and near‐infrared‐light emission and are potentially interesting for the application in “truly organic” light‐emitting devices. Lastly, they represent facile precursors to large polycyclic aromatic hydrocarbon (PAH) substituted porphyrins. We prepared the first tetra‐hexa‐peri‐hexabenzocoronene substituted porphyrin, which represents the largest prepared PAH‐porphyrin conjugate to date.     

Discrete particle swarm optimization based multi-objective service path constructing algorithm

Aiming at previous research primarily focused on constructing service paths with a single objective,for exam-ple,latency minimization,cost minimization or load balance,which ignored the overall performance of constructed ser-vice paths,a multi-objective service path constructing algorithm based on discrete particle swarm optimization (MOPSO) was proposed.To promote the convergence rate and improve constructing performance,the criterions for selecting can-didate physical nodes and paths were explored,and a particle position initialization and update strategy (PIFC) was de-signed.Simulation experiments show that the proposed algorithms can improve the overall quality of service paths and increase the success rate and long-term average revenue.