Abstract A catalyst free cycloaddition reaction of 3-oxo-1, 2-pyrazolidinium ylides with β- trifluoroacetyl vinyl ethyl ether is reported, which proceeded smoothly at ambient temperature and afford the bicyclic pyrazolidinone products in good yield. This is the first report of synthesis of 6-trifluoroacetyl substituted bicyclic pyrazolidinones that are potentially anti-microbial and herbicidal.
