The Experts below are selected from a list of 32949 Experts worldwide ranked by ideXlab platform
Daniel B. Werz - One of the best experts on this subject based on the ideXlab platform.
-
Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor-acceptor Cyclopropanes.
Beilstein Journal of Organic Chemistry, 2020Co-Authors: Grzegorz Mlostoń, Mateusz Kowalczyk, André U. Augustin, Peter G. Jones, Daniel B. WerzAbstract:Ferrocenyl thioketones reacted with donor-acceptor Cyclopropanes in dichloromethane at room temperature in the presence of catalytic amounts of Sc(OTf)3 yielding tetrahydrothiophene derivatives, products of formal [3 + 2]-cycloaddition reactions, in moderate to high yields. In all studied cases, dimethyl 2-arylCyclopropane dicarboxylates reacted with the corresponding aryl ferrocenyl thioketones in a completely diastereoselective manner to form single products in which (C-2)-Ar and (C-5)-ferrocenyl groups were oriented in a cis-fashion. In contrast, the same Cyclopropanes underwent reaction with alkyl ferrocenyl thioketones to form nearly equal amounts of both diastereoisomeric tetrahydrothiophenes. A low selectivity was also observed in the reaction of a 2-phthalimide-derived Cyclopropane with ferrocenyl phenyl thioketone.
-
FERROCENYL-SUBSTITUTED TETRAHYDROTHIOPHENES VIA FORMAL (3+2)-CYCLOADDITION REACTIONS OF FERROCENYL THIOKETONES WITH DONOR-ACCEPTOR CyclopropaneS
2020Co-Authors: Grzegorz Mlostoń, Mateusz Kowalczyk, André U. Augustin, Peter G. Jones, Daniel B. WerzAbstract:Abstract Ferrocenyl thioketones react with donor-acceptor Cyclopropanes in dichloromethane at room temperature in the presence of catalytic amounts of Sc(OTf)3 yielding tetrahydrothiophene derivatives, products of formal (3+2)-cycloaddition reactions, in moderate to high yields. In all studied cases, dimethyl 2-arylCyclopropane dicarboxylates react with corresponding aryl ferrocenyl thioketones in a completely diastereoselective manner to form single products in which (C-2)-Ar and (C-5)-ferrocenyl groups are oriented in a cis-fashion. In contrast, the same Cyclopropanes undergo reaction with alkyl ferrocenyl thioketones to form nearly equal amounts of both diastereoisomeric tetrahydrothiophenes. Low selectivity was also observed in the reaction of 2-phthalimide-derived Cyclopropane with ferrocenyl phenyl thioketone.
-
pd catalyzed three component coupling of terminal alkynes arynes and vinyl Cyclopropane dicarboxylate
Organic Letters, 2015Co-Authors: Lennart K B Garve, Daniel B. WerzAbstract:A palladium-catalyzed three-component coupling involving in situ generated arynes, terminal alkynes, and vinyl Cyclopropane dicarboxylate has been developed. The process demonstrates the first example of aryne chemistry combined with the ring opening of vinyl Cyclopropanes. This efficient method using readily available starting materials generates two new carbon–carbon bonds in one pot.
-
ein neues goldenes zeitalter in der chemie donor akzeptor substituierter Cyclopropane
Angewandte Chemie, 2014Co-Authors: Tobias F Schneider, Johannes Kaschel, Daniel B. WerzAbstract: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.
Igor V. Trushkov - One of the best experts on this subject based on the ideXlab platform.
-
Lewis Acid Triggered VinylCyclopropane–Cyclopentene Rearrangement
Journal of Organic Chemistry, 2017Co-Authors: Olga A Ivanova, Alexey O. Chagarovskiy, Vasiliy D. Krasnobrov, I. I. Levina, Alexey Shumsky, Igor V. TrushkovAbstract:We report a mild Lewis acid induced isomerization of donor–acceptor Cyclopropanes, containing an alkenyl moiety and diverse electron-withdrawing group(s) at the adjacent positions, into substituted cyclopentenes. We have found that 1,1,2-trisubstituted cyclopent-3-enes were exclusively obtained in yield of 51–99% when Cyclopropanes with a 2-substituted alkenyl group as a donor underwent isomerization. For Cyclopropanes bearing a trisubstituted alkenyl group either the corresponding cyclopent-3-enes or isomeric cyclopent-2-enes having two acceptor groups at the C(1) atom were formed, with the reaction selectivity being determined by the applied Lewis acid. We have shown that the reactivity of the donor–acceptor Cyclopropane increases with the increase of the electron-donating character of (hetero)aromatic group attached to the alkenyl moiety. The synthetic utility of the developed methodology was also demonstrated through the synthesis of polysubstituted cyclopentane and piperidine derivatives.
-
lewis acid catalyzed 3 4 annulation of 2 heteroaryl Cyclopropane 1 1 dicarboxylates with cyclopentadiene
Advanced Synthesis & Catalysis, 2011Co-Authors: Olga A Ivanova, Alexey O. Chagarovskiy, Igor V. Trushkov, Ekaterina M Budynina, Alexey E Kaplun, Mikhail Ya MelnikovAbstract:A novel Lewis acid-catalyzed [3+4] annulation of 2-(heteroaryl)Cyclopropane-1,1-dicarboxylates with cyclopentadiene is reported. This reaction proceeds via an electrophilic attack of the Lewis acid-activated donor-acceptor Cyclopropane onto cyclopentadiene followed by Friedel–Crafts intramolecular alkylation of the heteroarene substituent. This is the first general example of reactions of donor-acceptor Cyclopropanes wherein the donor substituent serves as a nucleophile. The described annulation represents a convenient approach to bicyclo[3.2.1]octa-2,6-dienes with heteroarenes annulated to C(2)-C(3) bond. Its efficiency was demonstrated for a series of furyl, thienyl, pyrrolyl, benzofuryl, benzothienyl, and indolyl substituted Cyclopropanes. Additionally, in the case of 2-(5-methyl-2-furyl)Cyclopropane-1,1-diester we observed the predominant formation of product of the [3+4] annulation or the tetracyclic 5,8-methanocyclopenta[a]azulene derivative, depending on the reaction conditions.
Yong Qin - One of the best experts on this subject based on the ideXlab platform.
-
recent applications of Cyclopropane based strategies to natural product synthesis
Synthesis, 2012Co-Authors: Pei Tang, Yong QinAbstract:Activated Cyclopropanes show versatile reactivity and are therefore powerful building blocks in organic chemistry and natural product synthesis. This review focuses on recent applications of Cyclopropane-based approaches to the syntheses of natural products. These applications include diverse processes involving cyclopropanation–ring-opening–cyclization or ring expansion to form key natural product skeletons. 1 Introduction 2 Formal Cycloaddition Strategies 2.1 Formal [3+2] Cycloaddition with Aldehydes and Ketones 2.2 Formal [4+3] Cycloaddition via Cope Rearrangement 2.3 Cycloaddition with Transition Metals 3 Cyclopropanation–Ring-Opening Strategies 4 Cyclopropanation–Ring-Opening–Cyclization Strategies 5 Ring Closing via Cyclopropanation 6 Conclusion
Olga A Ivanova - One of the best experts on this subject based on the ideXlab platform.
-
Lewis Acid Triggered VinylCyclopropane–Cyclopentene Rearrangement
Journal of Organic Chemistry, 2017Co-Authors: Olga A Ivanova, Alexey O. Chagarovskiy, Vasiliy D. Krasnobrov, I. I. Levina, Alexey Shumsky, Igor V. TrushkovAbstract:We report a mild Lewis acid induced isomerization of donor–acceptor Cyclopropanes, containing an alkenyl moiety and diverse electron-withdrawing group(s) at the adjacent positions, into substituted cyclopentenes. We have found that 1,1,2-trisubstituted cyclopent-3-enes were exclusively obtained in yield of 51–99% when Cyclopropanes with a 2-substituted alkenyl group as a donor underwent isomerization. For Cyclopropanes bearing a trisubstituted alkenyl group either the corresponding cyclopent-3-enes or isomeric cyclopent-2-enes having two acceptor groups at the C(1) atom were formed, with the reaction selectivity being determined by the applied Lewis acid. We have shown that the reactivity of the donor–acceptor Cyclopropane increases with the increase of the electron-donating character of (hetero)aromatic group attached to the alkenyl moiety. The synthetic utility of the developed methodology was also demonstrated through the synthesis of polysubstituted cyclopentane and piperidine derivatives.
-
lewis acid catalyzed 3 4 annulation of 2 heteroaryl Cyclopropane 1 1 dicarboxylates with cyclopentadiene
Advanced Synthesis & Catalysis, 2011Co-Authors: Olga A Ivanova, Alexey O. Chagarovskiy, Igor V. Trushkov, Ekaterina M Budynina, Alexey E Kaplun, Mikhail Ya MelnikovAbstract:A novel Lewis acid-catalyzed [3+4] annulation of 2-(heteroaryl)Cyclopropane-1,1-dicarboxylates with cyclopentadiene is reported. This reaction proceeds via an electrophilic attack of the Lewis acid-activated donor-acceptor Cyclopropane onto cyclopentadiene followed by Friedel–Crafts intramolecular alkylation of the heteroarene substituent. This is the first general example of reactions of donor-acceptor Cyclopropanes wherein the donor substituent serves as a nucleophile. The described annulation represents a convenient approach to bicyclo[3.2.1]octa-2,6-dienes with heteroarenes annulated to C(2)-C(3) bond. Its efficiency was demonstrated for a series of furyl, thienyl, pyrrolyl, benzofuryl, benzothienyl, and indolyl substituted Cyclopropanes. Additionally, in the case of 2-(5-methyl-2-furyl)Cyclopropane-1,1-diester we observed the predominant formation of product of the [3+4] annulation or the tetracyclic 5,8-methanocyclopenta[a]azulene derivative, depending on the reaction conditions.
Joseph Moran - One of the best experts on this subject based on the ideXlab platform.
-
Nucleophilic Ring Opening of Donor–Acceptor Cyclopropanes Catalyzed by a Brønsted Acid in Hexafluoroisopropanol
Organic Letters, 2018Co-Authors: Edward Richmond, Vuk Vukovic, Joseph MoranAbstract:A general, Brønsted acid catalyzed method for the room temperature, nucleophilic-ring opening of donor-acceptor Cyclopropanes in fluorinated alcohol solvent, HFIP, is described. Salient features of this method include an expanded Cyclopropane scope; including those bearing single keto-acceptor-groups, and those bearing electron deficient aryl-groups. Notably, the catalytic system proved amenable to a wide range of nucleophiles including arenes, indoles, azides, diketones and alcohols.
