نتایج جستجو برای: regio and chemoselective
تعداد نتایج: 16827812 فیلتر نتایج به سال:
Recent Visual and Infrared Thermal Imaging Spectrometer (VIRTIS) images from the Ve-nus Express mission found emissivity variations on the venusian surface that correlate with some volcanic edifices and coronae [1-3]. Increased emissivity was noted near Quet-zalpetlatl Coronae, Atete Corona, Mertseger Mons, Shiwanokia and Shulamite Coronae in Themis Regio, Idunn Mons, Hathor Mons and Ininni Mon...
Iso-butyric acid as a new, simple, and expensive solvent/catalyst was successfully used for the chemoselective Fischer’s synthesis of indolenines derivatives 3a-r by one-pot condensation reaction of various phenylhydrazines 1a-e with the substituted acetophenones 2a-c at reflux conditions. In this protocol, all products 3a-r were obtained in high yields and short reaction time. The structures o...
The Cassini Imaging Science Subsystem acquired high-resolution imaging data on the outer Saturnian moon, Phoebe, during Cassini's close flyby on 11 June 2004 and on Iapetus during a flyby on 31 December 2004. Phoebe has a heavily cratered and ancient surface, shows evidence of ice near the surface, has distinct layering of different materials, and has a mean density that is indicative of an ice...
An efficient procedure for the syntheses of pyrazolo[1,5-a]pyrimidines through reactions of 1,2-allenic ketones with aminopyrazoles under extremely mild conditions without using any catalyst or promoter has been developed. The reactions showed excellent regio-selectivity with all the allenic ketone substrates except for those bearing an alkyl group at the internal position of the allene moiety....
An efficient chemoselective process for the synthesis of 14- and 15-membered triazole-containing macrocycle compounds has been developed through the combination of two multicomponent reactions and an intramolecular Sonogashira cross-coupling reaction.
The cooperative catalysis of CpRu(PPh3)2(CH3CN)PF6 (1b) and DBU enables chemoselective nucleophilic activation of acetonitrile in the presence of base-sensitive aldehydes 2 to afford corresponding beta-hydroxynitriles in good yield.
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