Lewis Acid-Mediated Ring-Opening Reactions of <i>trans</i>-2-Aroyl-3-styrylcyclopropane-1,1-dicarboxylates: Access to Cyclopentenes and <i>E</i>,<i>E</i>‑1,3-Dienes

The ring-opening reaction of trans-2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates was investigated with different Lewis acids. With SnCl4, the cyclopropane dicarboxylates afforded cyclopentene derivatives through ring opening followed by cyclization (vinylcyclopropane–cyclopentene rearrangement). With TiCl4, they furnished E,E-1,3-diene derivatives stereoselectively via ring opening followed by proton elimination.