Reactions of β-Lactones with Lewis Acids: Ring Enlargement Versus β-Elimination

Article abstract of DOI:10.1016/0040-4039(95)00610-O

On treatment with MgBr2 the β-spirolactones 7 and 10 undergo ring enlargement to the γ-lactones 8 and 11, whereas the β-spirolactones 13 show diastereoselective β-elimination to form the β,γ-unsaturated acids 14.The lewis acid influence on the migratory aptitude of Me versus H is studied for β-lactone 18.