Sun J, Ye H, Zhang H, Wu XX. Palladium-Catalyzed Cyclization Coupling with Cyclobutanone-Derived
N-Tosylhydrazones: Synthesis of Benzofuran-3-Cyclobutylidenes and Spirocyclobutanes.
J Org Chem 2023;
88:1568-1577. [PMID:
36648061 DOI:
10.1021/acs.joc.2c02620]
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Abstract
A palladium-catalyzed cyclization coupling of iodoarene-tethered alkynes with cyclobutanone-derived N-tosylhydrazones is reported, providing a convenient and efficient approach to benzofuran-3-cyclobutylidenes. On this basis, spirocyclobutanes can be generated smoothly in an efficient cascade manner by the addition of dienophiles. Good yields and scalability are demonstrated. Sequential intramolecular carbopalladation, palladium-carbene migratory insertion, δ-hydride elimination, and cycloaddition processes are involved.
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