A New and Practical Five-Carbon Component for Metal-Catalyzed [5 + 2] Cycloadditions: Preparative Scale Syntheses of Substituted Cycloheptenones

Described herein is an efficient preparative scale synthesis of 1-(2-methyoxyethoxy)-1-vinylcyclopropane and the investigation of the utility of this reagent as a new five-carbon component in metal-catalyzed [5 + 2] cycloadditions. A new cycloaddition procedure is also described that proceeds up to 12-fold faster and with 10-fold less catalyst than previously described, providing cycloheptenones in many cases in minutes and in isolated yields of 75−97%. The procedure is readily conducted on a small or large scale (up to 100 mmol thus far).