DBU-Catalyzed Deconjugative Alkylations of 2-Alkylidene Indanones and Tetralones with Alkenes and Synthesis of Spirocyclic δ-Lactones

Abstract 1,8-Diazabicyclo(5.4.0)undec-7-ene catalyzes the deconjugative α-alkylation of 2-butylidene 1-indanone and 1-tetralone with electrophilic alkenes, to give α,α-disubstituted β,γ-unsaturated indanone and tetralone products, under mild conditions, and in moderate to excellent yields. Further elaboration of the 1-indanone and 1-tetralone-derived skipped enones gave δ,ɛ-unsaturated alkenoic acids, which underwent diastereoselective iodo- and epoxylactonizations, furnishing valuable [4.5]- and [5.5]-spirocyclic δ-lactones in high yields.