Lewis acid catalyzed tandem difunctionalization/fragmentation reactions of bicyclobutanes: access to 2-vinylidenyl 1,4-dicarbonyl compounds

Abstract

Strain-release-driven transformations of bicyclo[1.1.0]butanes (BCBs) have emerged as a highly effective strategy for generating chemical complexity under mild reaction conditions. Herein, we report a tandem ring-opening reaction of acyl BCBs with H₂O to construct synthetically versatile 2-vinylidenyl 1,4-dicarbonyl compounds. This process involves the generation of a cyclobutane intermediate, which contains a nucleophilic hydroxyl group (–OH) and a hypervalent iodine moiety [I^(III)(Ph)(OAc)], achieved through Lewis acid-catalyzed difunctionalization of the strained carbon–carbon σ-bond in BCBs. Subsequent Grob-type fragmentation yields the desired products. The reaction demonstrates broad functional group compatibility and has been successfully applied to complex molecular structures, enabling the synthesis of highly valuable 2-vinylidenyl 1,4-dicarbonyl compounds under mild conditions. Preliminary mechanistic investigations were conducted to support the proposed reaction pathway.