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