Synthesis of 1-Alkoxy-2,2-dicyanocyclobutanes by High Pressure Promoted Polar [2+2] Cycloadditions of Enol Ethers with 1,1-Dicyanoalkenes

Enol ethers are stereoselectively converted with 1,1-dicyanoalkenes into 1-alkoxy-2,2-dicyanocyclobutanes at 12 kbar pressure and temperatures up to 50-degrees-C. The main stereoisomer is mostly obtained pure in moderate to good yields by crystallization.