Author
Tobias F. Schneider
Other affiliations: Braunschweig University of Technology
Bio: Tobias F. Schneider is an academic researcher from University of Göttingen. The author has contributed to research in topics: Furan & Cyclopropanation. The author has an hindex of 13, co-authored 23 publications receiving 1462 citations. Previous affiliations of Tobias F. Schneider include Braunschweig University of Technology.
Topics: Furan, Cyclopropanation, Pyrrole, Ring (chemistry), Cyclopropane
Papers
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TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
805 citations
TL;DR: In this paper, the erforderliche Absenkung der Aktivierungsbarriere wird durch die Kombination von zueinander vicinal stehendem Elektronendonor and -akzeptor erreicht.
Abstract: Ringspannung gewinnbringend zu nutzen, ist seit jeher fur den Aufbau komplexer Systeme von grosem Vorteil. Schnell richtet sich somit der Blick auf Cyclopropane als Bausteine fur die organische Synthese. Auch wenn die Thermodynamik dabei auf der Seite des Synthesechemikers steht, ermoglicht erst ein spezielles Substitutionsmuster am Cyclopropan besonders milde, effiziente und selektive Umsetzungen. Die erforderliche Absenkung der Aktivierungsbarriere wird durch die Kombination von zueinander vicinal stehendem Elektronendonor und -akzeptor erreicht. Dieser Aufsatz beleuchtet die richtigen Hilfsmittel, um mit Donor-Akzeptor-substituierten Cyclopropanen Ringoffnungen, Cycloadditionen und Umlagerungen durchzufuhren.
222 citations
TL;DR: The first synthesis of anti-fused oligoannelated THF moieties is reported, consisting of cyclopropanation, reduction and oxidation, which allows the creation of oligoacetals up to a nonacyclic system.
90 citations
TL;DR: A detailed theoretical study of ring-enlargement reactions of 72 differently substituted donor-acceptor-substituted cyclopropanes is presented.
85 citations
TL;DR: Electron-rich oligopyrroles and pyrrolo[3,2-e]indoles are generated by a domino process induced by donor-acceptor-substituted cyclopropanes, thus allowing the introduction of nitrogen and aromaticity.
Abstract: Multiple displacement of oxygen: Electron-rich oligopyrroles and pyrrolo[3,2-e]indoles are generated by a domino process induced by donor-acceptor-substituted cyclopropanes. Up to seven molecules of water are eliminated, thus allowing the introduction of nitrogen and aromaticity.
85 citations
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
1,358 citations
TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
805 citations
TL;DR: A panoramic overview of recent progress in the most relevant areas related to such materials, including the polymerisation of natural monomers and their derivatives, the exploitation of biopolymers, as such, or after appropriate modifications, as well as the preparation of composites and blends, can be found in this article.
599 citations
TL;DR: This tutorial review focalizes on new intramolecular transformations of donor-acceptor cyclopropanes for cycloisomerizations, formal cycloadditions, umpolung reactions, rearrangements and ring-opening lactonizations/lactamizations from 2009 to 2013.
Abstract: Cyclization reactions of donor–acceptor (D–A) cyclopropanes are recognized as versatile methods for construction of carbocyclic and heterocyclic scaffolds. In the literature, many examples of these polarized cyclopropanes' reactivity with nucleophiles, electrophiles, and radicals are prevalent. Although intermolecular reactivity of donor–acceptor cyclopropanes is widely reported, reviews that center on their intramolecular chemistry are rare. Thereupon, this tutorial review focalizes on new intramolecular transformations of donor–acceptor cyclopropanes for cycloisomerizations, formal cycloadditions, umpolung reactions, rearrangements and ring-opening lactonizations/lactamizations from 2009 to 2013. Furthermore, the role of D–A acceptor cyclopropanes as reactive subunits in natural product synthesis is underscored.
475 citations