نتایج جستجو برای: heck reaction
تعداد نتایج: 413170 فیلتر نتایج به سال:
Aza-Heck cyclizations are an emerging method for the construction of chiral N-heterocyclic systems. In these processes, an activated N-O bond replaces the C-X bond (X = halide, OTf) used in conventional Heck reactions, with the associated aza-Pd(ii)-intermediate engaging pendant alkenes in a Heck-like manner. This perspective article commences with an historical overview of the area, which stem...
The tandem Heck-lactonization reaction between enoates Z-1a,b, E-1a, E-2a-d, Z-2e, 2f, and o-iodophenols (4a-f) was studied in the presence of substoichiometric amounts of Pd(OAc)(2) or PdCl(2), under experimental conditions favoring the cationic mechanism (conditions A, B, and C), leading to coumarins 5a-f and 6a-e. Moderate to excellent yields were obtained under aqueous conditions (condition...
This review describes the recent advances in the microwave-assisted synthesis of 7-membered and larger heterocyclic compounds. Several types of reaction for the cyclization step are discussed: Ring Closing Metathesis (RCM), Heck and Sonogashira reactions, Suzuki-Miyaura cross-coupling, dipolar cycloadditions, multi-component reactions (Ugi, Passerini), etc. Green syntheses and solvent-free proc...
A novel 1,4-palladium migration between the o- and o'-positions of biaryls has been observed in organopalladium intermediates derived from o-halobiaryls. The organopalladium intermediates generated by this migration have been trapped either by a Heck reaction employing ethyl acrylate or by Suzuki cross-coupling using arylboronic acids. This palladium migration can be activated or deactivated by...
An efficient palladium-catalyzed tandem approach for the synthesis of highly functionalized tetrahydroquinazolines 4a–q, and 5a–f by the reaction of o-haloanilines 1a–g with acrylates 2a–d and isothiocyanates 3aa–3ah/isocyanates 3ba–3bfvia Heck-conjoined amidation/thioamidation and concomitant chemoselective Michael-addition is described. A competitive experiment showed that isothiocyanates wer...
We have developed novel fluorogenic transformations based on formation of C C bonds catalyzed by palladium using iodocoumarin 1 as a model aryl iodide, where fluorescence is quenched completely due to effects of the heavy, polarizable iodine atom. Substitution of the iodine atom for the carbon using Sonogashira, Suzuki–Miyaura and Heck couplings results in a dramatic fluorescence enhancement. T...
The Heck coupling of aryl iodides with pyranoid glycals using a catalytic amount of Pd(OAc)(2) to form pyranoid aryl C-glycosides has been achieved. The reaction takes place smoothly in the presence of Ag(2)CO(3) and Cu(OAc)(2) (or DMSO) in acetonitrile. This arylation process, which occurs in a highly regio- and stereo-selective manner, provides a simple, mild, and efficient approach to the sy...
Axially chiral mono(NHC)-Pd(II) and mono(NHC)-Au(I) complexes with one side shaped 1,1'-biphenyl backbone have been prepared from chiral 6,6'-dimethoxybiphenyl-2,2'-diamine. The complexes were characterized by X-ray crystal structure diffraction. The Pd(II) complex showed good catalytic activities in the Suzuki-Miyaura and Heck-Mizoroki coupling reactions, and the (S)-Au(I) complexes also showe...
The optimization of multistep chemical syntheses is critical for the rapid development new pharmaceuticals. However, concatenating individually optimized reactions can lead to inefficient syntheses, owing interdependencies between steps. Herein, we develop an automated continuous flow platform simultaneous telescoped reactions. Our approach applied a Heck-cyclization-deprotection reaction seque...
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