Rhenium- and manganese-catalyzedreactions between beta-keto esters and acetylenes, followed by treatment with tetrabutylammonium fluoride, gave 2-pyranone derivatives regioselectively.
A reaction between a beta-keto ester and an acetylene in the presence of a rhenium complex, [ReBr(CO)(3)(thf)](2), as a catalyst, provided a 2-pyranone derivative in excellent yield via retro-aldol reaction (C-C single bond cleavage). By adding an acetylene-bearing ester group(s) after the formation of 2-pyranones, an aromatization reaction proceeded and multisubstituted aromatic compounds were obtained in good to excellent yields.