1,832 research outputs found
Rhodium-Catalyzed Annulation of 4‑Arylbut-3-yn-1-amines with Internal Alkynes through C–H Functionalization
No full textA new,
one-step rhodium(III)-catalyzed annulation of 4-arylbut-3-yn-1-amines
with internal alkynes through C–H functionalization is reported.
This reaction allows the formation of three new chemical bonds, including
two C–C bonds and one C–N band, thus selectively assembling
various spiro[indene-1,2′-pyrrolidine]s with excellent functional
group compatibility, high atom-economy, and step-efficiency
Cobalt-Promoted Electroreductive Cross-Coupling of Prop-2-yn-1-yl Acetates with Chloro(vinyl)silanes
No full textAn electroreductive cross-coupling of prop-2-yn-1-yl
acetates with
chloro(vinyl)silanes for producing tetrasubstituted silylallenes is
developed. The method enables the formation of a new CSi bond
through the cathodic reduction formation of the silyl radical, radical
addition across the CC bond, the alkenyl anion intermediate
formation, and deacetoxylation and represents a mild, practical route
to the synthesis of silylallenes. Mechanistic studies reveal that
CoCl2 acts as the mediator to promote the formation of
the alkenyl anion intermediate via electron transfer
Towards an integrated approach to industry dynamics and labour mobility
No full textIndustrial dynamics and labour mobility are two fields of economic research that have developed fast in recent years, but along what are essentially separate lines. This paper shows that the processes those two fields deal with can be highly interdependent, and demonstrates the usefulness of (and the opportunity for) an integrated approach to the dynamics of industries and labour mobility. It concludes with a list of questions that inform a research agenda dedicated to such approach.
Microanalytical study of Er-doped LiNbO3 crystals obtained by Er-Li ion exchange
No full textErbium-doped lithium niobate (LiNbO3) crystals were produced by Er±Li ion exchange (IE) process. The role of the process parameters such as exchange time and temperature, crystal cu direction,composition and heating rate of the Er ions liquid source was investigated by means of secondary ion mass spectrometry, X-ray diffraction (XRD) and microluminescence techniques. We demonstrated that Er effective diffusion coefficient is two orders of magnitude greater with respect to the thermal diffusion from Er film. We observed that no Li deficient phase can be achieved and that active Er ions are homogeneously incorporated in the substrate. The method is suitable for Er doping of LiNbO3 crystals at relative low temperature (from 570°C to 650°C)
Iron-Catalyzed Synthesis of Benzosultams from <i>N</i>‑Phenyl‑<i>N</i>‑(prop-2-yn-1-yl)benzenesulfonamide and Benzenesulfonyl Hydrazine
No full textA novel route for an iron-catalyzed tandem sulfonylation,
C(sp2)–H activation, cyclization reaction which
uses N-phenyl-N-(prop-2-yn-1-yl)benzenesulfonamide
and benzenesulfonohydrazide to synthesize derivatives of (Z)-2-phenyl-4-((phenylsulfonyl)methylene)-3,4-dihydro-2H-benzo[e][1,2]thiazine 1,1-dioxide has
been developed. The method features convenient operation and good
functional group tolerance. In addition, it employs insensitive and
inexpensive FeSO4 as the catalyst and provides a direct
approach for the preparation of benzothiazides
Growth temperature effect on the optical and material properties of AlxInyGa1-x-yN epilayers grown by MOCVD
No full textAlxInyGa1-x-yN epilayers have been grown by metalorganic chemical vapor deposition (MOCVD) at different temperatures from 800 to 870degreesC. The incorporation of indium is found to increase with decreasing growth temperature, while the incorporation of Al remains nearly constant. The optical properties of the samples have been investigated by photoluminescence (PL) and time-resolved photoluminescence (TRPL) at different temperatures. The results show that the sample grown at 820 C exhibits the best optical quality for its large PL intensity and the absence of the yellow luminescence. Furthermore the temperature-dependent PL and TRPL of the sample reveals its less exciton localization effect caused by alloy fluctuations. In the scanning electron microscopy measurement, much uniform surface morphology is found for the sample grown at 820degreesC, in good agreement with the PL results, The improvement of AlxInyGa1-x-yN quality is well correlated with the incorporation of indium into AlGaN and the possible mechanism is discussed. (C) 2002 Elsevier Science B.V. All rights reserved
Large excitation-power dependence of pressure coefficients of InxGa1-xN/InyGa1-yN quantum wells
No full textExcitation-power dependence of hydrostatic pressure coefficients (dE/dP) of InxGa1-xN/InyGa1-yN multiple quantum wells is reported. When the excitation power increases from 1.0 to 33 mW, dE/dP increases from 26.9 to 33.8 meV/GPa, which is an increase by 25%. A saturation behavior of dE/dP with the excitation power is observed. The increment of dE/dP with increasing carrier density is explained by an reduction of the internal piezoelectric field due to an efficient screening effect of the free carriers on the field
Mg acceptor energy levels in AlxInyGa1-x-yN quaternary alloys: An approach to overcome the p-type doping bottleneck in nitrides
No full textThe Mg-Ga acceptor energy levels in GaN and random Al8In4Ga20N32 quaternary alloys are calculated using the first-principles band-structure method. We show that due to wave function localization, the MgGa acceptor energy level in the alloy is significantly lower than that of GaN, although the two materials have nearly identical band gaps. Our study demonstrates that forming AlxInyGa1-x-yN quaternary alloys can be a useful approach to lower acceptor ionization energy in the nitrides and thus provides an approach to overcome the p-type doping difficulty in the nitride system
Cascade Nucleophilic Attack/Addition Cyclization Reactions to Synthesize Oxazolidin-2-imines via (<i>Z</i>)‑2-Bromo-3-phenylprop-2-en-1-ols/3-phenylprop-2-yn-1-ols and Diphenyl Carbodiimides
No full textTwo concise strategies to synthesize oxazolidin-2-imines
by cascade
nucleophilic attack/addition cyclization reactions of (Z)-2-bromo-3-phenylprop-2-en-1-ols/3-phenylprop-2-yn-1-ols and diphenyl
carbodiimides without a transition-metal catalyst have been developed.
The reactions exhibited good substrate applicability tolerance, and
a variety of substituted (Z)-4-((Z)-benzylidene)-N,3-diphenyloxazolidin-2-imines were
synthesized in moderate to excellent yields with good stereoselectivity.
The reports also provided a convenient strategy to synthesize 3-phenylprop-2-yn-1-ols
by (Z)-2-bromo-3-phenylprop-2-en-1-ols. The economic
and practical methods provide a great advantage for potential industrial
synthesis of oxazolidin-2-imines
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