Palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate with C5-substituted Meldrum's acids: Rapid access to δ-lactones

A novel method for constructing δ-lactone derivatives through Pd-catalyzed [4 + 2] cycloaddition of 2-alkylidenetrimethylene carbonates (ADTMCs) with C5-substituted Meldrum's acid derivatives has been reported. This transformation proceeds under mild conditions to afford diverse δ-lactone architectures in moderate to good yields (up to 89 %). This protocol demonstrates broad substrate scope, accommodating various electronically and sterically differentiated Meldrum's acid derivatives, all readily prepared from commercially available materials.