Regioselective Synthesis of (E)-5-(Tributylstannylmethylidene)-5H-furan-2-ones and (E)-3-(Tributylstannylmethylidene)-3H-isobenzofuran-1-ones: Easy Access to γ-Alkylidenebutenolide and Phthalide Skeletons
(<i>E</i>)-5-(Tributylstannylmethylidene)- 5<i>H</i>-furan-2-ones: Versatile Synthons for the Stereospecific Elaboration of γ-Alkylidenebutenolide Skeletons
[GRAPHICS]Stereoselective construction of (E)-gamma-tributylstannylmethylidene butenolides 1 was achieved through the palladium-catalyzed tandem cross coupling/cyclization reactions of tributylstannyl 3-iodopropenoate derivatives with tributyltinacetylene. Iododestannylation of 1 occurs with inversion of the configuration of the exocyclic double bond while the observed selectivity in the Stille reaction was found to be dependent on the nature of the aryl halide.