Recursive Anion-Triggered Tandem Reactions of ortho -Bis-ynones: Tunable Synthesis of 1-Indenones and Cyclopenta[ a ]inden-8(2 H )-ones.

Recursive anion-mediated activation of o -bis-ynones sets off a Michael addition-aldol reaction-dehydrative rearrangement cascade, leading to the one-pot synthesis of 1-indenones via orthogonal interplay between the two ortho -ynone moieties. Repeating the recursive anion engagement with the 1-indenones unfolded access to a functionally embellished cyclopenta[ a ]inden-8(2 H )-one core and its spiroannulated analogues either directly or stepwise through tandem 1,6-Michael-type addition-6π electrocyclization and an in situ oxidation sequence.