Extended RDMA flaps can be effectively applied in the reconstruction of finger defects beyond PIP joint. Its advantages include a simple dissection, single-stage reconstruction, and preservation of digital artery and nerve. The donor site can be primarily closed if the flap width is less than 3 cm. Multiple subcutaneous heparin injection is a preferred solution in cases where venous congestion occurs in the flap.
Herein, we describe
an efficient nanocopper-catalyzed Alder-ene
reaction of allenynamides. The copper nanoparticles were immobilized
on amino-functionalized microcrystalline cellulose. A solvent-controlled
chemoselectivity of the reaction was observed, leading to the chemodivergent
synthesis of pyrrolines (2,5-dihydropyrroles) and pyrroles. The heterogeneous
copper catalyst exhibits high efficiency and good recyclability in
the Alder-ene reaction, constituting a highly attractive catalytic
system from an economical and environmental point of view.
A novel catalytic enantioselective methodology based on synergistic catalysis for the synthesis of chiral 2-acyl pyridines and pyrazines is reported. The strategy involves the metal-Lewis acid activation of acetyl aza-arenes and the secondary-amine activation of enals. The proposed mechanism is supported by DFT calculations.
An asymmetric synthesis of α-spiro-δ-lactam via organocascade reaction from easily accessible starting materials is reported. The catalytic sequence undergoes enantioselective Michael addition of β-ketoamide to α,β-unsaturated aldehyde catalysed by a secondary amine catalyst, followed by hemiaminal annulation. Optically enantiopure compounds with three stereogenic centres are obtained in good yields and excellent selectivities (up to >20:1 dr and up to >99% ee).
A catalytic asymmetric strategy for the total synthesis of quinuclidine natural products, which includes the completed enantioselective synthesis of the classical targets quinine and quinidine is disclosed. It is based on catalytic asymmetric cascade transformations, which paves the road for the synthesis of both enantiomers of the crucial C4 stereocenter with high enantioselectivity (up to 99 % ee) in one pot. Next, developing a route to all possible stereoisomers of a common early‐stage intermediate sets the stage for the total synthesis of different enantiomers or epimers of quinine, quinidine and analogues with high selectivity.
The discovery and investigation of solvent dependency in stereoselective intramolecular amidation of chiral 5-aminofunctionalized-2-fluoromalonate ester derivatives, which gives access to highly functionalized δ-lactams with a quaternary fluorine-containing stereocenter, is disclosed. Experimental work together with density functional theory calculations led to understanding of how to direct and switch the stereochemical outcome of the stereoselective δ-lactam formation. The merging of this solvent-dependent stereoselective switch with asymmetric catalysis and cascade reactions gives access to an unprecedented strategy for stereodivergent synthesis of all possible stereoisomers of fluorine-containing stereocenters adjacent to tertiary stereocenters of a wide range of heterocyclic compounds with 95-> 99% ee in one-pot. It is also useful for application in total synthesis of fluorine-containing pharmaceuticals.
In this work we present a formal [3+2] cycloaddition based on synergistic catalysis. Vinylcyclopropanes derived from cyanoesters reacts with enals by dual activation using Pd(0) and secondary amines to form the cyclopentanes in good yields and stereoselectivities.
In this work, eight different types of optical oxygen sensing films were prepared by impregnating indicator and matrix solution on the surface of a polypropylene microporous filter membrane. The polymer matrix of the sensing films was ethyl cellulose (EC), polymethyl methacrylate (PMMA), and their blends with different mixing ratios. Scanning electron microscopy (SEM), laser confocal microscopy, and fluorescence spectrometer were used to investigate the morphologies and optical properties of the sensing films. Phase delay measurements under different oxygen partial pressures (PO2) and temperatures were applied to investigate the analytical performances of the sensing film for gaseous O2 monitoring. Results show that the response time of all the sensing films was extremely fast. The sensitivities and dynamic ranges of the sensing films with the blended polymer matrix were separately decreased and increased as the EC/PMMA ratio decreased, and the S-V curve of the sensing films blended with equal content of EC and PMMA exhibited good linearity under different temperatures, showing a promising prospect in practical application.
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