Stereoselective Synthesis of 2-(β-Aroylstyryl)malonates and γ-Butyrolactones through Lewis Acid-Mediated Ring-Opening Reactions of Aroyl-Substituted Donor–Acceptor Cyclopropanes

Aroyl-substituted donor–acceptor cyclopropanes when treated with AlCl 3 in 1,2-DCE under reflux conditions afforded E -2-(β-aroylstyryl)malonates stereoselectively through ring-opening followed by elimination of proton. On the other hand, when treated with GaCl 3 in 1,2-DCE at room temperature, they furnished tri-substituted γ-butyrolactones diastereoselectively through ring-opening followed by ring-expansion via malonate oxygen (Cloke–Wilson rearrangement).