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Fully Substituted Pyranones via Quasi-Heterogeneous Genuinely Ligand-Free Migita–Stille Coupling of Iodoacrylates

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posted on 06.02.2015, 00:00 by Jiří Kratochvíl, Zdeněk Novák, Mukund Ghavre, Lucie Nováková, Aleš Růžička, Jiří Kuneš, Milan Pour
Migita–Stille coupling of (Z)-β-iodoacrylates with (E)-α-stannyl allylic alcohols to furnish 5-alkylidene-4-substituted-5,6-dihydro-2H-pyran-2-ones is efficiently catalyzed by 2% Pd black in DMF, while Pd­(PPh3)4 is inactive. Heterogeneous Pd released in solution is most likely responsible for the catalysis. The reaction is applicable to other substrates, without having to resort to ligands, additives, and/or solid support for Pd. The resulting pyranones can be rearranged to fully functionalized pyranones in another single step.