Abstract: The hydrohalogenation-dehydrohalogenation of 3- methylenecyclobutanecarbonitriles provides a facile, high-yield synthesis of 3-methylbicyclo [l. lO] butanecarbonitriles. The latter react with a broad spectrum of reagents including acids, electron-deficient multiple bonds, nucleophiles, free radicals, and halogens to give cyclobutanes and cyclobutenes. The bicyclobutane ring system is thermally labile leading ...