نتایج جستجو برای: syntheses
تعداد نتایج: 11788 فیلتر نتایج به سال:
This brief review gives an overview of newer developments in (18)F-chemistry with the focus on small (18)F-labelled molecules as intermediates for modular build-up syntheses. The short half-life (<2 h) of the radionuclide requires efficient syntheses of these intermediates considering that multistep syntheses are often time consuming and characterized by a loss of yield in each reaction step. R...
The structure of anisomycin has been determined by X-ray investigation4 and the absolute configuration was confirmed by chemical correlation.5 Anisomycin has attracted considerable synthetic interest, and several synthetic studies, derivative syntheses as well as total syntheses, have been reported.6 Especially, the synthesis of its analogues has revealed the structure-activity relationship of ...
Total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) were accomplished by a sequence that employs an intramolecular dipolar cycloaddition of an azomethine imine intermediate to form the azatricyclic moiety and establish the relative configuration of the spiropiperidine ring. These syntheses, together with the synthesis of the originally purported structure 1 of nankakurine A, rigo...
The cyanine dyes Cy3 and Cy5 have proven valuable in numerous applications involving conjugation with proteins. Practical syntheses of lysine-selective, succinimidyl ester derivatives of these dyes have been published, and succinimidyl esters are commercially available. However, the published syntheses of cysteine-selective derivatives produce relatively low yields from expensive starting mater...
The first total syntheses of welwitindolinone A and the most complex members of the fischerindole family, fischerindoles I and G, are reported. Highlights of these short, protecting-group-free syntheses include the application of the recently developed direct indole-carbonyl coupling, a simple approach for installing the quaternary center with neighboring chlorine atom, a regioselective dehydro...
Highly concise syntheses of (+)-macrosphelides A and B were accomplished in this study. The key feature of our synthetic route involved the direct three-carbon homologation of the readily available Weinreb amide 6 by the addition of a trans-vinylogous ester anion equivalent and facile construction of the 16-membered macrolide skeleton of macrosphelides via an intramolecular nitrile oxide-olefin...
background the need for competence training and development in health management and leadership workforces has been emphasised. however, evidence of the outcomes and impact of such training and development has not been systematically assessed. the aim of this review is to synthesise the available evidence of the outcomes and impact of training and development in relation to the competence of he...
The present review discusses the known synthetic routes to the lamellarin alkaloids published until 2014. It begins with syntheses of the structurally simpler type-II lamellarins and then focuses on the larger class of the 5,6-saturated and -unsaturated type-I lamellarins. The syntheses are grouped by the strategy employed for the assembly of the central pyrrole ring.
sulfuric acid {[3-(3-silicapropyl)sulfanyl]propyl}ester (saspspe) is employed as a recyclable catalyst for the synthesis of α-amino nitriles. these syntheses were performed via a one-pot three-component condensation of aldehydes, amines, and trimethylsilyl cyanide under mild reaction conditions at room temperature. the catalyst could be recycled and reused several times without any loss of effi...
An efficient, mild and environmentally friendly method was developed for the Strecker reaction to synthesize α-aminonitriles in the presence of methyl imidazolium hydrogen sulfate ([Hmim][HSO4]) as an efficient catalyst. These syntheses were performed via a one-pot three-component condensation of aldehydes (or ketones), amines, and trimethylsilyl cyanide under mild and solvent free c...
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