1,721,176 research outputs found
Critical surveys covering the year 2006: introduction and transformation of functional groups
No full textintroduction and transformation of functional groups are describe
Asymmetric organocatalysis: From infancy to adolescence
No full textAfter an initial period of validating asymmetric organocatalysis by using a wide range of important model reactions that constitute the essential tools of organic synthesis, the time has now been reached when organocatalysis can be used to address specific issues and solve pending problems of stereochemical relevance. This Review deals with selected studies reported in 2006 and the first half of 2007, and is intended to highlight four main aspects that may be taken as testimony of the present status and prospective of organocatalysis: a) chemical efficiency; b) discovery of new substrate combinations to give new asymmetric syntheses; c) development of new catalysts for specific purposes by using mechanistic findings; and d) applications of organocatalytic reactions in the asymmetric total synthesis of target natural products and known compounds of biological and pharmaceutical relevance. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA
Polymer supported reagents in synthesis: Preparation of bicyclo[2.2.2]octane derivatives via tandem Michael addition reactions and subsequent combinatorial decoration
No full textPreparation of bicyclo[2.2.2]octane derivatives via tandem Michael addition reactions is reporte
Design and Synthesis of New Classes of Heterocycle Glycoconjugates and Amino Acid by Asymmetric Multicomponent Reactions (AMCRs)
No full textMulticomponent Syntheses of glycoside-decorated N-heterocyclic pharmacophores
No full textWe report in this communication on the synthesis of carbohydrate decorated N-heterocycles, namely dihydropyrimidin-2-ones, dihydropyridines, and azetidin-2-ones, via multicomponent Biginelli, Hantzsch, and Staudinger reactions respectively
Design and Synthesis of New Classes of Heterocycle C-Glycoconjugates, and Carbon-Linked Sugar and Heterocycle Amino Acids by Asymmetric Multicomponent Reactions (AMCRs)
No full textWhile chemical efficiency relies on several factors, the multi-component reaction (MCR) approach was considered as a powerful synthetic tool for preparing target molecules of biological relevance in an efficient manner. Four classes of new bioactive molecules were designed and synthesized by asymmetric MCRs, in some cases with the cooperation of polymer-assisted solution-phase (PASP) technique. These include (a) C-glycosyl dihydropyrimidines and dihydropyridines via Biginelli and Hantzsch cyclocondensations, (b) C-glycosyl β-amino acids via Mannich- and Reformatsky-type reactions, (c) C-glycosyl β-lactams via Staudinger reaction, and (d) heterocyclic α-amino acids (glycine and alanine) via the Biginelli and Hantzsch reactions. © 2006 American Chemical Society
Parallel Solution-Phase Syntheses of Functionalised Bicyclo[2.2.2]octanes: Generation of a Library Using Orchestrated Multi-Step Sequences of Polymer Supported Reagents and Sequestrants
No full textA parallel Solution-Phase Syntheses of Functionalised Bicyclo[2.2.2]octanes is reporte
Synthesis of Heterocycle-Linked C-Glycosyl alpha-Amino Acids and C-Glycopeptides
No full textNon-natural C-glycosyl alpha-amino acids are building-blocks for the co-translational modification of natural glycopeptides. These are key components of the complex machinery that operates in vital processes of all living organisms, ranging from eubacteria to eukaryotes. While a wide range of C-glycosyl amino acids have been synthesized, we have designed and prepared a small collection of a new class of these amino acids whose structure features a heterocycle ring holding the carbohydrate and the amino acid fragments. Isoxazole, triazole, tetrazole, and pyridine moieties were used as suitable linkers in this project owing to their easy construction via Huisgen cycloaddition and Hantzsch multicomponent reaction. Details on the synthesis of each family of these glycolconjugates are given below, some emphasis being given to the efficiency and generality of each method employed. The potential of these glycosyl amino acids in non-natural glycopeptide synthesis is exemplified by the coupling of a pyridine-linked derivative with two natural amino acids to give a non-natural glycotripeptide
Design and characterization of new materials for the assembly of micro and nano-devices: the gateway toward improved and novel applications in medicinal, life, and environmental sciences
No full textStereoselective synthesis of the C-linked analogue of β-D-galactopyranosyl-L-serine
No full textThe coupling of the D-serinal derivative 7 with the D-galactopyranosylmethylene phosphorane generated from the phosphonium salt 6 and reduction of the resulting alkene led to the C-glycosylated amino alcohol 9 that in turn was oxidized to the title amino acid in 44% overall yield
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