Palladium-Catalyzed 6-<i>endo</i>-Selective Oxycyclization-Alkene Addition Cascades of<i>ortho</i>-Alkynylarylcarboxamides and α,β-Unsaturated Carbonyl Compounds
作者:Youssef Madich、Rosana Álvarez、José M. Aurrecoechea
DOI:10.1002/ejoc.201500797
日期:2015.10
cyclization–coupling cascade reactions between ortho-alkynylarylcarboxamides and methyl vinyl ketone or acrylaldehyde are described. An initial 6-endo-oxypalladation of the triple bond is followed by a C–C coupling to give structurally diverse isochromenimines (and related heterosubstituted derivatives), in which the α,β-unsaturated carbonyl moiety is incorporated as an alkyl-type exocyclic side chain. The coupling
A three-component, one-pot, stepwise Sonogashira-heterocyclization-Heck-coupling process was developed starting from either haloarenecarboxamides, halophenols or haloanilines, terminal alkynes and electron-deficient alkenes. Cyclic imidate-, benzofuran-, or indole-type products are obtained, respectively, in useful yields, being typically better than those obtained with isolation of the intermediate Sonogashira adducts. Very high 6-endo selectivity is maintained with imidate-type coupling products despite the presence of copper salts carried over from the Sonogashira coupling.