This article presents selective transformations of some readily available cyclodienes through simple chemical procedures into novel functionalized small-molecular entities. The syntheses hereby described involved selective cycloadditions, followed by ring-opening metathesis of the resulting β-lactam or isoxazoline derivatives and selective cross-metathesis by differentiation of the olefin bonds on the alkenylated heterocycles. The cross-metathesis transformations have been detailed, which were performed under various experimental conditions with the aim of exploring chemodiscrimination of the olefin bonds and delivering the corresponding functionalized β-lactam or isoxazoline derivatives.
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http://dx.doi.org/10.1002/tcr.202000070 | DOI Listing |
J Org Chem
December 2024
School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China.
A novel and highly efficient Pd-catalyzed approach for the synthesis of bis-heterocycles featuring both isoxazoline and methyleneindole motifs is demonstrated. The in situ formation of vinyl Pd(II) species through an alkyne-tethered carbamoyl chloride cyclization is crucial, and the innovative Pd-catalyzed carboetherification of β,γ-unsaturated oximes with vinyl Pd(II) species has been developed. This method is not only operationally straightforward but also exhibits a broad substrate scope and excellent functional group tolerance.
View Article and Find Full Text PDFRSC Adv
December 2024
Faculty of Pharmaceutical Sciences, Setsunan University 45-1 Nagaotoge-cho Hirakata Osaka 573-0101 Japan
Electrophilic aromatic substitution at the C5 position of isoxazolines and construction of a new quaternary carbon center were achieved in this paper. This is the first report of carbon-carbon (C-C) bond formation onto isoxazoline without compromising the ring structure. Various aromatics including heteroaromatics gave the desired products in good yields, especially aromatics bearing electron-donating groups.
View Article and Find Full Text PDFMolecules
November 2024
MSO, Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, Le Mans Université, Avenue O. Messiaen, 72085 Le Mans, CEDEX 9, France.
Oximation of substituted ketofurfuryl alcohols in the presence of hydroxylamine hydrochloride and pyridine in ethanol as solvent led to a new class of spiro derivatives presenting a 7-methylene-1,6-dioxa-2-azaspiro [4.4] nona-2,8-diene skeleton along with, in some cases, the predictable oxime. The structures of such spiro compounds were determined by 2D NMR spectroscopy.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, University of Illinois Chicago, 845 West Taylor Street, MC 111, Chicago, Illinois 60607, United States.
A diastereoselective addition and rearrangement reaction has been developed for the synthesis of pyrrolidine-2-ylidenes from N-isoxazolines and electron-deficient allenes. This method proceeds via the rearrangement of a proposed -alkenylisoxazoline intermediate to generate densely functionalized pyrrolidine-2-ylidenes under simple catalyst-free conditions that tolerate ketone substituents and install relative stereochemistry at positions 3 and 4 of the heterocycle. Reaction optimization and the substrate scope are described in addition to studies evaluating the reactivity of the -dione and enaminone groups of the products.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
Stereoselective alkene 1,2-difunctionalization is a privileged strategy to access three-dimensional C(sp)-rich chiral molecules from readily available "flat" carbon feedstocks. State-of-the-art approaches exploit chiral transition metal-catalysts to enable high levels of regio- and stereocontrol. However, this is often achieved at the expense of a limited alkene scope and reduced generality.
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