Abstract
Intermolecular cycloadditions catalyzed by transition-metal complexes are powerful methods for convergent synthesis of cyclic materials. In this context, we recently devised γ-methylidene-δ-valerolactones as new reagents for intermolecular decarboxylative cyclization reactions with several reaction partners to produce various cyclic compounds under palladium catalysis. These lactones effectively serve as precursors for 1,4-zwitterionic species through oxidative addition to palladium(0) and successive decarboxylation, thereby introducing a four-carbon unit in a newly formed cyclic framework. In some cases, however, they provide three carbons in a cyclic framework with a spirocyclopropane moiety. Herein we describe an overview of the reactions using these lactones, including some asymmetric variants as well as mechanistic insights for these decarboxylative cyclization reactions.
