Abstract: a,@-Unsaturated ketones or aldehydes form a 1: 2 complex with ethylaluminum dichloride which reacts with alkenes either intermolecularly or intramolecularly to give a zwitterion. The zwitterion collapses reversibly to a cyclobutane in geometrically favorable cases and undergoes hydride and alkyl shifts to generate a,@-unsaturated carbonyl compounds. The intramolecular reactions proceed with high regia-and stereospecificity ( ...
