نتایج جستجو برای: isocyanates
تعداد نتایج: 1001 فیلتر نتایج به سال:
Novel bisimide-fused acenes were synthesized via bismuth triflate mediated double-cyclization reaction of acid chlorides and isocyanates. Their optical and electrical properties revealed significantly smaller HOMO-LUMO gaps compared with those of their parent acenes. Fabricated OFET based on tetracene bisimide showed n-type OFET outputs.
This review highlights structural and biosynthetic work on a group of nitrogen-functionalised terpenes that are almost exclusively found in marine invertebrates and the animals that feed on them. The chemical functionality reviewed includes isocyanides, isothiocyanates, formamides, thiocyanates, isocyanates, and dichloroimines. The literature through mid 2003 is reviewed and there are 143 citat...
An optically active helical poly(phenylacetylene) was synthesized by the copolymerization of phenylacetylenes bearing optically active hydroxy or ester groups obtained by the kinetic resolution of a racemic phenylacetylene with lipase; the helix-sense was inverted from one helix to another by the further chemical modification of the hydroxy groups with achiral bulky isocyanates or an acid chlor...
Alkoxydienamides 2 have been synthesized exploiting the reactivity of α,β-unsaturated acetals 1 with isocyanates in the presence of Schlosser's superbase LIC-KOR. In a mild acidic medium, 2 can then be promptly converted both into α-ketoamides 3 and into substituted 2-pyrrolidinones 4 or imino ethers 5 by choosing the appropriate experimental conditions.
The heteroleptic calcium amides [{ArNC(Me)CHC(Me)NAr}Ca(NR(2))(THF)] (Ar=2,6-di-iso-propylphenyl, R=SiMe(3), Ph) and the homoleptic heavier alkaline earth amides, [M{N(SiMe(3))(2)}(2)] (M=Ca, Sr and Ba) are reported as pre-catalysts for the hydroamination of isocyanates.
A palladium-catalyzed decarboxylative cyclopropanation of 2-alkylidenetrimethylene carbonates with isocyanates is described to form oxazolidinones of (1-aminocyclopropyl)methanols with high selectivity. The site of nucleophilic attack is directed by connecting the two reaction components and by employing an electron-deficient triarylphosphine ligand.
Isocyanates, isothiocyanates, and carbodiimides are effective substrates in (3 + 2) cycloadditions with donor-acceptor cyclopropanes for the synthesis of five-membered heterocycles. These reactions exhibit a broad substrate scope, high yields, and well-defined chemoselectivity. Discussed herein are the implications of Lewis acid choice on the stereochemical outcome and the reaction mechanism.
[RhCp*(OAc)(2)(H(2)O)] [Cp* = pentamethylcyclopentadienyl] catalyzed the C-H bond amidation of ferrocenes possessing directing groups with isocyanates in the presence of 2 equiv/Rh of HBF(4)·OEt(2). A variety of disubstituted ferrocenes were prepared in high yields, or excellent diastereoselectivities.
A palladium-catalyzed asymmetric synthesis of 2-pyrrolidinones with a quaternary stereocenter at the 3-position has been achieved by the reaction of γ-methylidene-δ-valerolactones with alkyl isocyanates. High enantioselectivity has been realized by employing a newly synthesized chiral phosphoramidite ligand.
PURPOSE Isocyanates are highly reactive chemicals used in a number of industries including paints. Therefore, house painters are known to be at risk for occupational exposure to isocyanates. Our objectives in this study were: (1) to investigate the possible effects of isocyanate exposition on the bronchoalveolar epithelial permeability in house painters by using Tc-99m DTPA radioaerosol lung sc...
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