Results 1 to 10 of about 25,988 (120)
Dearomative (3 + 2) Cycloadditions of Unprotected Indoles
Organic Letters, 2022 The (3 + 2) cycloaddition of various indoles with a dithioallyl cation affords dearomatized cyclopentannulated adducts, with complete control of regioselectivity and excellent chemo- and diastereoselectivity. The success of the reaction critically relies on the use of an excess of very strong Brønsted acid, which paradoxically prevents carbocationic ...
Bram Ryckaert +3 more
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Intramolecular Oxyallyl–Carbonyl (3 + 2) Cycloadditions [PDF]
Journal of the American Chemical Society, 2013 Cycloadditions involving oxyallyl intermediates typically require an electron-rich diene or alkene, but we have discovered the first examples of the cycloaddition of heteroatom-stabilized oxyallyls onto carbonyl groups. An oxazolidinone-substituted oxyallyl undergoes chemoselective (3 + 2) cycloaddition onto the carbonyl group of a tethered dienone in ...
Krenske, Elizabeth H. +5 more
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Conjugation of Nucleosides and Oligonucleotides by [3+2] Cycloaddition
The Journal of Organic Chemistry, 2007 A procedure is presented for copper(I)-catalyzed [3+2] cycloaddition of nucleosides and nucleotides in near-quantitative yield. Azido-alkyne cycloaddition was applied for the preparation of a range of adenosine dimers and derivatives with versatile functionality, as well as for the smooth condensation of two oligonucleotide strands.
Jawalekar, A.M. +6 more
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Intramolecular Ynamide–Benzyne (3+2) Cycloadditions
Angewandte Chemie, 2023 AbstractWe report herein intramolecular (3+2) cycloaddition reactions between ynamides as three‐atom components and benzyne. In these intramolecular reactions, the two‐bond formation is realized by exploiting benzyne precursors that contain a chlorosilyl group as a linking functionality.
Tsukasa Tawatari +4 more
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[3 + 2]-Cycloadditions of Azomethine Imines and Ynolates [PDF]
Organic Letters, 2016 A novel [3 + 2]-cycloaddition between azomethine imines and lithium ynolates is described to synthesize bicyclic pyrazolidinones. These bicyclic pyrazolidinones are versatile intermediates to form β-amino acids and monocyclic pyrazolidinones. High diastereoselectivity and stereospecificity allow access to optically active products.
Sarah E, Winterton, Joseph M, Ready
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(3+2)-Cycloaddition Reactions of Oxyallyl Cations [PDF]
Synthesis, 2014 The (3+2)-cycloaddition reaction involving oxyallyl cations has proven to be a versatile and efficient approach for the construction of five-membered carbo- and heterocycles, which are prevalent frameworks in natural products and pharmaceuticals. The following article will provide a brief summary of recent disclosures on this process featuring chemo ...
Hui, Li, Jimmy, Wu
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[3 + 2]-Cycloaddition reaction of sydnones with alkynes [PDF]
Beilstein Journal of Organic Chemistry, 2018 This review covers all known examples of [3 + 2]-cycloaddition between sydnones and both terminal as well as internal alkynes/cycloalkynes taken from literature since its discovery by Huisgen in 1962 up to the current date. Except enumeration of synthetic applications it also covers mechanistic studies, catalysis, effects of substituents and reaction ...
Veronika Hladíková +2 more
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Synthesis of Dihydrobenzisoxazoles by the [3 + 2] Cycloaddition of Arynes and Oxaziridines [PDF]
The Journal of Organic Chemistry, 2010 Dihydrobenzisoxazoles are readily prepared in good yields by the [3 + 2] cycloaddition of oxaziridines and arynes. The reaction involves an unusual cleavage of the C-O bond of the oxaziridine and tolerates a variety of substituents on the oxaziridine and the o-(trimethylsilyl)aryl triflate to form aryl-, heteroaryl-, alkyl-, and naphthyl-substituted ...
Kivrak, Arif, Larock, Richard C.
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3-Oxidopyraziniums – [4+2] versus [3+2] cycloadditions [PDF]
Arkivoc, 2007 The reaction of 1,5,6-trimethyl-3-oxidopyrazinium with methyl methacrylate provides the first example of such a species reacting in a cycloaddition as a 2-azadiene (4+2), as opposed to a 1,3- dipole (3+2).
Zarina Joomun +4 more
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Alkaloid synthesis via [3+2] cycloadditions [PDF]
Pure and Applied Chemistry, 2002 Abstract Tin-lithium exchange on (2-azaallyl)stannanes affords nonstabilized 2-azaallyllithiums (2-azaallyl anions) that undergo [π4s+π2s] cycloadditions with alkenes to afford pyrrolidines. The scope of this method has been expanded to include 2-azapentadienyllithiums and heteroatom-substituted 2-azaallyllithiums.
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