Alkynes to Vinyl Lactones

The addition of sodium benzenetellurolate to 3-hydroxy-1-propynes produces (Z)-2-hydroxyalkylethenyl phenyl telluriums. These compounds treated with carbon monoxide in dichloromethane in the presence of stoichiometric amounts of triethylamine and palladium(II) chloride are carbonylated and the resulting acids converted to lactones.  

With catalytic amounts of palladium(II) chloride with copper(II) chloride as oxidant, the yields of the lactones were reduced to half of the yields obtained with stoichiometric amounts of palladium(II) chloride.  

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