4-Ethenylidene-2-oxazolidinones 2, 6, and 9 are prepared in reasonable yields by the reaction of 2-butyn-1,4-diol biscarbamates in the presence of catalytic amounts of Pd 2 (dba) 3 CHCl 3 (0.005 equiv) and triethylamine (0.1 equiv). The allenic three carbons are not aligned straight, but considerably distorted (173.6°); the enamine double bond is reactive toward unsaturated amides (providing 4) and methyl vinyl ketone (providing 10).