نتایج جستجو برای: diels alder and 1 3 dipolar cycloaddition reactions
تعداد نتایج: 17429646 فیلتر نتایج به سال:
The general approach of using a bicyclic template to produce inhibitors of the protease superfamily of enzymes has been investigated. The Diels Alder cycloaddition reaction on solid support has been found to be highly efficient for the synthesis of libraries of compounds that mimic the beta-strand secondary structure of proteins. Several potent and selective inhibitors of proteases have been di...
Cycloaddition of 3,4-dibromofuran with azo diesters proceeds by a Diels–Alder reaction followed by a novel rearrangement to give 3,5dibromotetrahydropyridazin-4-ones. Variable-temperature NMR spectroscopy shows four separate conformations at low temperature attributed to restricted rotation about the carbamate functions. The ethyl compound decomposes upon storage with loss of the carbamate grou...
An enantioseletive, biomimetic synthesis of (-)-longithorone A has been achieved using an intermolecular/transannular Diels-Alder sequence which provides some support for the proposed biosynthesis. The cycloaddition precursors were two [12]-paracyclophanes that were constructed with atropisomer control during ene-yne metathesis macrocyclizations.
the utilization of substitued dienes with electron-donor groups and under high pressure conditions, induces the dienophilic character of 1-nitronaphtalene in Diels-Alder reactions, giving the products with and without the nitro-group, the yield depending on the nature of the dienes substituent groups. Introduction The Diels-Alder reaction has been subject of extensive studies for both theoretic...
Here, we present a simple, modular and efficient strategy that allows the 3'-terminal labeling of DNA, regardless of whether it has been chemically or enzymatically synthesized or isolated from natural sources. We first incorporate a range of modified nucleotides at the 3'-terminus, using terminal deoxynucleotidyl transferase. In the second step, we convert the incorporated nucleotides, using e...
Predictions from DFT (B3LYP/6-31 G(d))-computed stereoisomer product distributions for intramolecular Diels-Alder (IMDA) reactions have been successfully replicated in the laboratory. Benzo-tethered hexadienyl acrylates generally undergo moderately trans-selective IMDA reactions which, as suggested by DFT calculation, arise from two opposing transition structure (TS) features: stabilising secon...
The amino acid proline catalyzed the three- and five-component cascade olefination-Diels-Alder-epimerization and olefination-Diels-Alder-epimerization-olefination-hydrogenation reactions of readily available precursors enones 1a-i, arylaldehydes 2a-k, alkyl cyanoacetates 3a-e and Hantzsch ester 9 to furnish highly substituted prochiral 1-cyano-4-oxo-2,6-diaryl-cyclohexanecarboxylic acid alkyl e...
In this update on the Diels-Alder reaction we would like to present an overview on how this very important reaction has progressed in the last decade, since the last spate of monographs and reviews appeared in the literature, and which deal with the reaction in the overall sense. Initially we present the Diels-Alder reaction in a generalised form, much as discovered over seventy years ago, so t...
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