Palladium-CatalyzedSequential Assembly of NucleophilicLactone-Embedded Benzofulvenes with π–Allylic Speciesand Nucleophiles

Compared with previously electrophilic benzofulvenes with exclusive reaction regioselectivity of the exocyclic double bond, novel lactone-embedded benzofulvenes with nucleophilicity and unique chemical properties have been designed and utilized in palladium-catalyzed sequential assembly with π-allylic species and various nucleophiles (including methoxide anion, alcohols, anilines, and alkylamines) through an unprecedented tandem allylation/ester bond cleavage process probably via a key oxocarbenium ion. The protocol featured high chemoselectivity and regioselectivity, constructing an array of densely functionalized indenes in high yields. Furthermore, the biological evaluation revealed that the synthesized indenes exhibited antitumor activity.