Highly Efficient Ultrasonic‐Assisted CuCl‐Catalyzed 1,3‐Dipolar Cycloaddition Reactions in Water: Synthesis of Coumarin Derivatives Linked with 1,2,3‐Triazole Moiety

By introducing ultrasound irradiation into “on water” CuCl‐catalyzed 1,3‐dipolar Huisgen cycloaddition, the reaction efficiencies were notably promoted toward a wide variety of applicable azides and alkynes at room temperature, and a series of coumarin derivatives linked with 1,2,3‐triazole moiety were synthesized using the optimized conditions.     

A Facile Synthesis of Novel Allenylphosphinates Containing Multi Potential Asymmetric Centers

The novel allenylphosphinates containing up to three axial and phosphorus asymmetric centers were prepared in excellent yields via the reactions of 6‐chloro‐6H‐dibenzo[c,e][1,2]oxaphosphinine to propargyl alcohols. During the process, the configuration of phosphorus determined the biphenyl axial chirality, stereospecifically forming (l)‐stereomers but did not influence the chirality of allenyl axis.     

Efficient Regioselective Synthesis of the Crotonyl Polydatin Prodrug by <Emphasis Type="Italic">Thermomyces lanuginosus</Emphasis> Lipase: a Kinetics Study in Eco-friendly 2-Methyltetrahydrofuran

Bio-based solvents have recently been discussed as sustainable green and promising alternatives to conventional organic media for enzymatic processes. In this paper, highly regioselective synthesis of the 6″-O-crotonyl-polydatin catalyzed by Thermomyces lanuginosus lipase (TLL) in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was successfully performed for the first time. The results indicated that TLL lipase displayed significantly improved catalytic performance in 2-MeTHF than in other traditional solvents. Under the optimal conditions, the initial reaction rate, 6″-regioselectivity, and maximum substrate conversion were as high as 12.38 mM h^?1, 100 %, and 100 %, respectively. Moreover, further investigations on the operational stability, kinetic parameters like V _max, K _m, V _max/K _m, and E _a revealed that 2-MeTHF exhibited excellent biocompatibility and rendered the greener process of the enzymatic acylation.     

Coupled intramolecular/heterointerfacial electron transfer in polyelectrolyte-shielded Iso-type black phosphorus hetero-structure boosts oxygen reduction kinetics

Searching new structured black phosphorus (BP) and exploring intriguing functions and applications have become a hot topic so far.Here,we introduce a novel Iso-...     

Nickel(II) complexes bearing pyrazolylimine ligand: synthesis,structure, and catalytic properties for vinyl‐type polymerization of norbornene

Two nickel(II) complexes of {2‐[C₃HN₂(R₁)₂‐3,5]}[C(R₂)?N(C₆H₃ⁱPr₂‐2,6)]NiBr₂ (complex 1 : R₁ = CH₃, R₂ = 2,4,6‐trimethylphenyl; complex 2 : R₁ = R₂ = Ph) were synthesized and characterized. The solid‐state structure of complex 1 has been confirmed by X‐ray single‐crystal analysis. Activated by methylaluminoxane (MAO), complexes 1 and 2 are capable of catalyzing the polymerization of norbornene with moderate activities [up to 10.56 × 10⁵ gPNBE (mol Ni h)^?1] with high molecular weights (M_w?13.56 × 10⁵ g mol^?1) and molecular weight distributions were around 2. The influences of polymerization parameters such as reaction temperature and Al–Ni molar ratio on catalytic activity and molecular weight of the polynorbornene were investigated in detail. The obtained polynorbornenes were characterized by means of ¹H‐NMR and FTIR techniques. The analytical results of polymer structures indicated that the norbornene polymerization is vinyl‐type polymerization rather than ROMP. Copyright © 2009 John Wiley & Sons, Ltd.     

Diastereoselective cycloadditions of a soluble polymer-supported substituted allyl alcohol derived from Baylis-Hillman reaction with nitrile oxides

A diastereoselective cycloaddition of a soluble polymer-supported Baylis-Hillman adduct with nitrile oxides is described. The reaction has shown to proceed with moderate diastereoselectivity, favoring the syn isomer of the resulting 3,5-substituted isoxazolines. The stereochemistry of the products has been assigned using ¹H NMR studies. The structure of one of the diastereomers has been determined by single-crystal X-ray crystallographic analysis.