Topic
1,3-Dipolar cycloaddition
About: 1,3-Dipolar cycloaddition is a research topic. Over the lifetime, 5560 publications have been published within this topic receiving 98615 citations.
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TL;DR: This work reveals that the LUMO-lowering activation of α,β-unsaturated aldehydes using the reversible formation of iminium ions with chiral imidazolidinones 1 is a valuable platform for the development of enantioselective organocatalytic Diels−Alder reactions.
Abstract: Our laboratory has been engaged in the design of broadly useful new strategies for enantioselective catalysis that utilize organic chemicals as reaction catalysts. In our recent study, we reported that the LUMO-lowering activation of α,β-unsaturated aldehydes using the reversible formation of iminium ions with chiral imidazolidinones 1 (eq 1) is a valuable platform for the development of enantioselective organocatalytic Diels−Alder reactions (eq 2). In this work, we reveal that this catalytic strategy is also amenable to [3 + 2] cycloadditions between nitrones and α,β-unsaturated aldehydes to provide isoxazolidines (eq 3), useful synthons for the construction of biologically important amino acids, β-lactams, amino carbohydrates, and alkaloids. To our knowledge, this is the first example of an organocatalytic 1,3-dipolar cycloaddition. Moreover, this study further documents that chiral amines can be employed as asymmetric catalysts for a range of transformations that traditionally utilize metal salts.
392 citations
TL;DR: In this paper, a detailed discussion on the application of [3+2] dipolar cycloaddition reactions in targeted syntheses is presented, and a detailed analysis of the performance of the [3 + 2] reaction is presented.
366 citations
TL;DR: Recent developments in catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides are highlighted, with special focus on contributions improving the structural scope at the dipolarophile and azometHine yLide partners.
347 citations
TL;DR: In addition to the tris(triazolylamines) previously reported, two types of compounds were found to exhibit significant ligand-accelerated catalysis, with one complex showing especially dramatic rate enhancements.
Abstract: Copper-based catalysts for the 1,3-dipolar cycloaddition of azides and alkynes were screened in parallel fashion using a fluorescence quenching assay. The method was designed to identify systems able to accelerate the coupling of reactants at micromolar concentrations in aqueous mixtures and to obtain quantitative comparisons of their activities. In addition to the tris(triazolylamines) previously reported, two types of compounds (bipy/phen and 2-pyridyl Schiff bases) were found to exhibit significant ligand-accelerated catalysis, with one complex showing especially dramatic rate enhancements. Preliminary explorations of the dependence of reaction rate on pH, ligand:Cu ratio, and Cu concentration are described.
339 citations
334 citations