Stereoretentive Olefin Metathesis Made Easy: In Situ Generation of Highly Selective Ruthenium Catalysts from Commercial Starting Materials

Beneficial structural motifs from two known state-of-the-art olefin metathesis catalysts types, bearing unsymmetrical N-heterocyclic carbenes (uNHCs), were combined into a new hybridized design thereby translating the complementary beneficial reactivity demonstrated by their ‘parent’ complexes to the new N-fluorene derived olefin metathesis catalysts. Two chelating 2-iso-propoxy-benzylidene (Hoveyda-type) and two 3-phenyl-1H-inden-1-ylidene (indenylidene-type) complexes were successfully prepared by in situ generation of either the N′-mesityl (Mes) or N′-diisopropylphenyl (Dipp) derived uNHCs taking advantage of the thermal decomposition of the corresponding 2-(penta-fluorophenyl)-imidazolidines (NHC adducts). The new fluorene-derived catalysts mediate challenging olefin metathesis processes, such as α-olefin self-metathesis, with high selectivity and conversion.

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In Situ Generation of Active Sites in Olefin Metathesis

Journal of the American Chemical Society ◽

10.1021/ja3011989 ◽

2012 ◽

Vol 134 (28) ◽

pp. 11462-11473 ◽

Cited By ~ 95

Author(s):

Kazuhiko Amakawa ◽

Sabine Wrabetz ◽

Jutta Kröhnert ◽

Genka Tzolova-Müller ◽

Robert Schlögl ◽

...

Keyword(s):

Olefin Metathesis ◽

Active Sites ◽

In Situ Generation

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Highly diastereo- and enantioselective organocatalytic synthesis of trifluoromethylated erythritols based on the in situ generation of unstable trifluoroacetaldehyde

Organic & Biomolecular Chemistry ◽

10.1039/d0ob02067b ◽

2021 ◽

Author(s):

Kazumasa Funabiki ◽

Toshiya Gotoh ◽

Ryunosuke Kani ◽

Toshiyasu Inuzuka ◽

Yasuhiro Kubota

Keyword(s):

Trifluoromethyl Group ◽

In Situ Generation

A highly diastereo- and enantioselective organocatalytic method to synthesise erythritols bearing a trifluoromethyl group has been investigated.

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Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

10.26434/chemrxiv.7130801.v1 ◽

2018 ◽

Author(s):

Haley Albright ◽

Paul S. Riehl ◽

Christopher C. McAtee ◽

Jolene P. Reid ◽

Jacob R. Ludwig ◽

...

Keyword(s):

Lewis Acid ◽

Olefin Metathesis ◽

Acid Activation ◽

Lewis Acid Catalysts ◽

Distinct Mode ◽

Aliphatic Ketones ◽

Carbon Carbon Bond ◽

Metathesis Reactions ◽

Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

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Recent advances in Minisci-type reactions and applications in organic synthesis

Current Organic Chemistry ◽

10.2174/1385272824999201230211157 ◽

2020 ◽

Vol 24 ◽

Author(s):

Wengui Wang ◽

Shoufeng Wang

Keyword(s):

Free Radical ◽

Hydrogen Atom ◽

Organic Synthesis ◽

Radical Reactivity ◽

Atom Loss ◽

Radical Generation ◽

In Situ Generation ◽

Thermal Cleavage ◽

Synthetic Chemist

Abstract:: Minisci-type reactions have become widely known as reactions that involve the addition of carbon-centered radicals to basic heteroarenes followed by formal hydrogen atom loss. While the originally developed protocols for radical generation remain in active use today, in recent years by a new array of radical generation strategies allow use of a wider variety of radical precursors that often operate under milder and more benign conditions. New transformations based on free radical reactivity are now available to a synthetic chemist looking to utilize a Minisci-type reaction. Radical-generation methods based on photoredox catalysis and electrochemistry, which utilize thermal cleavage or the in situ generation of reactive radical precursors, have become popular approaches. Our review will cover the remarkably literature that has appeared on this topic in recent 5 years, from 2015-01 to 2020-01, in an attempt to provide guidance to the synthetic chemist, on both the challenges that have been overcome and applications in organic synthesis.

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