نتایج جستجو برای: unsymmetrical
تعداد نتایج: 1532 فیلتر نتایج به سال:
5-Alkenyl-15-alkynylporphyrins have been obtained unexpectedly by [2 + 2] acid-catalyzed condensation of dipyrrylmethane and TMS propynal in addition to 5,15-dialkynylporphyrin, and the unsymmetrical porphyrin can be converted to a butadiyne-linked dimer by selective desilylation of the alkynyl TMS.
Stable, water-soluble aminosugar staurosporine, K-252a and rebeccamycin analogs have been prepared by nucleophilic opening of C(2)-symmetric N-activated bis-aziridines by bis-indolylmaleimides. This divergent strategy allows the synthesis of unsymmetrical substituted derivatives and provides an easy access to the piperidine and pyrrolidine analogs.
The transformation of enynes under cobalt-catalysis leads to symmetrical benzannulation products in dichloromethane. In tetrahydrofuran the cobalt-catalysed reactions afforded the unprecedented unsymmetrical benzannulation products in moderate to good yields and good regioselectivities. In addition, cyclotrimerisation of the alkyne subunit can be realised when electron-deficient enynes are appl...
A new tetra-dentate unsymmetrical Schiff base, C(15)H(10)N(4)O, has been synthesized from 4,5-dicyano-o-phenyl-enediamine and o-vanillin in refluxing ethanol. The dihedral angle between the two benzene rings is 39.0 (1)°. There are intra-molecular O-H⋯N and weak inter-molecular N-H⋯O and N-H⋯N inter-actions.
The synthesis of imidazolinium salts from the reaction of formamidines and (2-bromoethyl)diphenylsulfonium triflate is described. A variety of symmetrical and unsymmetrical imidazolinium triflate salts were synthesized in high yield in short reaction times under mild conditions. Aromatic and aliphatic N-substituents work well. The reaction is proposed to proceed via generation of a vinyl sulfon...
The prevention of environmental damage in durable unsymmetrical huge-capacitor (UHC) with α-MnO2 nanotubes and amorphous Fe2O3 nanotubes grown on flexible carbon fabric is first designed and fabricated. The assembled novel flexible UHC device with an extended operating voltage window of 1.6 V exhibits excellent performance such as a high energy density of 0.55 mWh/cm3 and good rate capability. ...
A series of unsymmetrical silicon(IV) phthalocyanines with a permethylated β-cyclodextrin unit and a sugar or a diamino moiety as the axial substituents have been prepared. These compounds are highly photocytotoxic with IC(50) values as low as 21 nM, which is ca. sevenfold lower than those of the symmetrical bis(cyclodextrin) analogue.
Sequential borylation of a first aryl iodide using a dialkylaminoborane followed by a Suzuki-Miyaura cross coupling of second aryl iodide ended up with an efficient, selective and practical synthesis of unsymmetrical biaryls. This tandem coupling shows a wide range of applicability.
The cation of the title salt, C(34)H(45)N(2) (+)·PF(6) (-), is a protonated form of an unsymmetrical overcrowded β-imino-amine. The observed bond lengths [C-N = 1.326 (4)-1.341 (4) Å and C-C = 1.383 (4)-1.391 (4) Å] suggest significant delocalization within the π system of the N C C C N backbone.
An efficient procedure has been developed for the preparation of tetrasubstituted unsymmetrical 1,4-enediones via copper-promoted autotandem catalysis and air as the oxidant. Various N-nucleophiles are compatible with this reaction, such as morpholine, piperidine, pyrrolidine, arylamines, pyrazole, imidazole, benzimidazole, and benzotriazole. This reaction also has significant advantages in eas...
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