Author
Ursula Streit
Bio: Ursula Streit is an academic researcher from University of Fribourg. The author has contributed to research in topics: Alkene & Cycloaddition. The author has an hindex of 3, co-authored 5 publications receiving 104 citations.
Topics: Alkene, Cycloaddition
Papers
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TL;DR: This short review aims to demonstrate the synthetic power of three different modes of photocycloaddition with benzene derivatives withBenzene derivatives.
Abstract: In the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.
77 citations
TL;DR: A new intramolecular para cycloaddition of arenes with allenes, yielding attractive rigid scaffolds bearing several reactive functionalities to build in further diversity, and was scaled up to multigram quantities without erosion of the typically high yields in photocycloadducts.
Abstract: In this work, we report on a new intramolecular para cycloaddition of arenes with allenes, yielding attractive rigid scaffolds bearing several reactive functionalities to build in further diversity. Bicyclo[2.2.2]octadiene-type products and benzoxepine acetals are formed in this reaction, in ratios and yields depending on the substitution pattern on the aromatic ring, the nature of the chromophore, and the tether. This unprecedented reaction has remarkable features that distinguish it from many other photochemical transformations: it is particularly robust with respect to substituents, it can be scaled up without a notable loss of efficiency, and it can lead to structures with a high degree of complexity in low to good yields. All photochemical precursors could be synthesized readily in three steps. We confirmed the compatibility of the nitrogen atom in the photocycloaddition step, which gives access to a bicyclo[2.2.2]octadiene scaffold with two points that allow further diversification. This reaction wa...
24 citations
TL;DR: The photocycloaddition of alkenes with aromatic systems may proceed through three reaction modes, affording different types of products: ortho, meta, and para as discussed by the authors.
Abstract: The photocycloaddition of alkenes with aromatic systems may proceed through three reaction modes, affording different types of products: ortho, meta, and para. These reactions generate a considerable increase in complexity, and yield products arduously attainable by classical synthetic steps. Whereas the meta-photocyclo-addition has gained a lot of attention in the last decades because of its applicability in the total synthesis of numerous natural products, the ortho- and para-cycloadditions still have a great potential for further development. In this highlight, we review the latest advances in the field of photocycloaddition of alkenes to aromatic systems.
22 citations
TL;DR: In the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3+2] or meta, and the [4+2]-or para-photonicity.
Abstract: In the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.
1 citations
TL;DR: The photocycloaddition of alkenes with aromatic systems may proceed through three reaction modes, affording different types of products: ortho, meta, and para as discussed by the authors.
Abstract: The photocycloaddition of alkenes with aromatic systems may proceed through three reaction modes, affording different types of products: ortho, meta, and para. These reactions generate a considerable increase in complexity, and yield products arduously attainable by classical synthetic steps. Whereas the meta-photocyclo-addition has gained a lot of attention in the last decades because of its applicability in the total synthesis of numerous natural products, the ortho- and para-cycloadditions still have a great potential for further development. In this highlight, we review the latest advances in the field of photocycloaddition of alkenes to aromatic systems.
1 citations
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TL;DR: This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds for complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.
Abstract: The use of photochemical transformations is a powerful strategy that allows for the formation of a high degree of molecular complexity from relatively simple building blocks in a single step. A central feature of all light-promoted transformations is the involvement of electronically excited states, generated upon absorption of photons. This produces transient reactive intermediates and significantly alters the reactivity of a chemical compound. The input of energy provided by light thus offers a means to produce strained and unique target compounds that cannot be assembled using thermal protocols. This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds. Synthetic designs based on photochemical transformations have the potential to afford complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.
692 citations
TL;DR: The most important photochemical transformations that have been employed in natural product synthesis are presented and selected total syntheses are discussed as examples, with particular attention given to the photochemical key step and its stereoselectivity.
Abstract: Photochemical reactions contribute in a significant way to the existing repertoire of carbon-carbon bond-forming reactions by allowing access to exceptional molecular structures that cannot be obtained by conventional means. In this Review, the most important photochemical transformations that have been employed in natural product synthesis are presented. Selected total syntheses are discussed as examples, with particular attention given to the photochemical key step and its stereoselectivity. The structural relationship between the photochemically generated molecule and the natural product is shown, and, where necessary, the consecutive reactions in the synthesis are illustrated and classified.
605 citations
TL;DR: Excited State Aromaticity and Antiaromaticity : Opportunities for Photophysical and Photochemical Rationalizations opens up new opportunities for photophysical and photochemical rationalizations.
Abstract: Excited State Aromaticity and Antiaromaticity : Opportunities for Photophysical and Photochemical Rationalizations
255 citations
TL;DR: This review highlights advances both in the area of dearomatization methodologies for the most chemically inert arenes and in synthetic applications of such strategies.
Abstract: Dearomatization reactions provide a synthetic connection between readily available, simple aromatic starting materials and more saturated intermediates of greater molecular complexity and synthetic utility. The last decade has witnessed a steady increase in the development of dearomative methods, providing new synthetic approaches to high-value building blocks and natural products. This review highlights advances both in the area of dearomatization methodologies for the most chemically inert arenes and in synthetic applications of such strategies.
232 citations
TL;DR: In this article, die wichtigsten Umsetzungen der photochemie vorgestellt, die auf breiter Front Einzug in die Naturstoffsynthese gehalten haben.
Abstract: Photochemische Reaktionen bereichern in signifikanter Weise das Repertoire zur Knupfung von Kohlenstoff-Kohlenstoff-Bindungen und machen ungewohnliche, auf herkommlichem Weg nicht erhaltliche Molekulgeruste zuganglich. In diesem Aufsatz werden die wichtigsten Umsetzungen der Photochemie vorgestellt, die auf breiter Front Einzug in die Naturstoffsynthese gehalten haben. Beispielhaft werden einzelne Totalsynthesen diskutiert, wobei besonderes Augenmerk auf den photochemischen Schlusselschritt sowie dessen Stereoselektivitat gerichtet ist. Dabei wird das photochemisch erzeugte Molekul in Relation zur Struktur des Naturstoffs gebracht, und Folgereaktionen werden, wo notwendig, illustriert und klassifiziert.
149 citations