نتایج جستجو برای: regio and chemoselective
تعداد نتایج: 16827812 فیلتر نتایج به سال:
Adsorbate conformation determines catalytic chemoselectivity: crotonaldehyde on the Pt(111) surface.
Molecular orientation, which depends on surface coverage, determines whether or not catalytic hydrogenation is chemoselective.
We describe the application of a new class of ligands--the phosphite-oxazole/imidazole (L1-L5a-g)--in asymmetric intermolecular Pd-catalyzed Heck reactions under thermal and microwave conditions. These ligands combine the advantages of the oxazole/imidazole moiety with those of the phosphite moiety: they are more stable than their oxazoline counterparts, less sensitive to air and other oxidizin...
CuO-CeO2 nanocomposite is reported as a green recyclable catalyst for the chemoselective synthesis of pentaerythritol diacetals from aromatic aldehydes under solvent-free conditions. The catalyst was synthesized by co-precipitation method and characterized by XRD, BET specific surface area, FESEM and EDS analysis. This procedure provides some advantages such as simple work-up, clean procedure, ...
A rapid and chemoselective method for the N-formylation of structurally diverse anilines with formic acid using nanoalumina sulfonic acid (NASA) at 70oC under solvent-free condition has been developed. The catalyst was found to be compatible with different functional groups and the formylation proceeded smoothly with anilines bearing electron withdrawing as well as electron donating substituents.
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...
The chemoselective [4+2] vs. [2+2] cycloaddition between allenoates and dithioesters can be controlled by switching the nucleophilic amine catalyst. The two modes of cyclizations represent the first example of controllable and chemoselective annulations between allenoates and dienophiles catalyzed by amine. These cyclizations are useful in offering a divergent synthesis of sulfur-containing het...
A simple route to the introduction of a number of chemoselective functional groups into peptoids (oligo(N-substituted glycines)) by an extension of the standard solid-phase submonomer method is reported. The following groups were introduced: aminooxyacetamide, N-(carbamoylmethyl)acetohydrazide, mercaptoacetamide, 2-pyridinesulfenylmercaptoacetamide, and aldehyde-terminated peptoids. The method ...
found on furrow and crater floors. We also find high albedo During its first two encounters with Ganymede, the Galileo units which include crater rims, furrow rims, and isolated knobs and massifs. Other features include an intermediate albedo spacecraft obtained images of a 16,500 km portion of Galileo Regio, a large expanse of dark terrain, at high resolution (76–86 lobate feature interpreted ...
C60 bis-adduct containing a mixture of regio-isomers with different LUMO energy levels and steric geometries could greatly affect the morphological and bulk properties. To investigate the regio-isomer effect on solar cell performance, we have successfully designed and synthesized a regio-selective 4-acetatephenyl-4'-methylphenylmethano C60 bis-adduct (S-APM-CBA) by "tether-directed remote funct...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید