A Pd-catalyzed 3,4-regioselective cyclopropanation of 2-substituted 1,3-dienes by decomposition of diazo esters is reported. The vinylcyclopropanes generated are isolated in practical chemical yields with high levels of regioselectivity but low diastereoselectivity. The system operates under mild reaction conditions, is scalable, and tolerates various sensitive functional groups. A series of original postcatalytic derivatizations is presented to highlight the synthetic potential of the catalytic method.
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http://dx.doi.org/10.1021/acsorginorgau.3c00024 | DOI Listing |
Chemistry
February 2024
INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), Normandie Univ., 76000, Rouen, France.
The catalytic asymmetric synthesis of highly functionalized cyclopropanes from 2-substituted allylic derivatives is reported. Using ethyl diazo acetate, the reaction, catalyzed by a chiral ruthenium complex (Ru(II)-Pheox), furnished the corresponding easily separable cis and trans cyclopropanes in moderate to high yields (32-97 %) and excellent ee (86-99 %). This approach significantly extends the portfolio of accessible enantioenriched cyclopropanes from an underexplored class of olefins.
View Article and Find Full Text PDFACS Org Inorg Au
October 2023
Department of Organic Chemistry, University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva, Switzerland.
A Pd-catalyzed 3,4-regioselective cyclopropanation of 2-substituted 1,3-dienes by decomposition of diazo esters is reported. The vinylcyclopropanes generated are isolated in practical chemical yields with high levels of regioselectivity but low diastereoselectivity. The system operates under mild reaction conditions, is scalable, and tolerates various sensitive functional groups.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2023
Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland, 97074, Würzburg, Germany.
Chemistry
April 2023
Albert-Ludwigs-Universität Freiburg, Institute of Organic Chemistry, Albertstraße 21, 79104, Freiburg im Breisgau, Germany.
A 1,3-carbocarbonation of 2-substituted cyclopropane 1,1-dicarboxylates introduces various saturated or unsaturated carbon residues at the 1- and 3- position of the former three-membered ring. Under copper catalysis, ring-opening attack with a Grignard reagent proceeded smoothly; the intermediate was converted to the final product by reaction with appropriate carbon-based electrophiles under basic conditions. As nucleophiles, Grignard reagents derived from sp -, sp -, and sp-hybridized carbon residues were successfully employed, whereas various aliphatic bromides and EBX derivatives (for sp moieties) served as electrophiles.
View Article and Find Full Text PDFOrg Lett
July 2022
Departament de Química Física i Inorgànica, University Rovira i Virgili, 43007 Tarragona, Spain.
Palladium catalyzes the cyclopropanation of 2-substituted 1,1-diborylalkenes with (trimethylsilyl)diazomethane. The relative stereoselectivity is controlled via a carbene insertion sequence generating an exclusive conformation between the R and SiMe substituents. Mixed 1,1-diborylalkenes also contributed to the formation of stereoselective B, B, Si-cyclopropanes.
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