Convenient Synthesis of Triphenylphosphanylidene 1′,3′-Dihydrospiro[cyclopentane-1,2′-inden]-2-enes via Three-Component Reaction

Abstract

The three-component reaction of triphenylphosphine, dialkyl acetylenedicarboxylate, and 2-arylideneindane-1,3-dione in dry DME at 0 °C to room temperature resulted in functionalized 4-(triphenyl-λ⁵-phosphanylidene)-1′,3′-dihydrospiro[cyclopentane-1,2′-inden]-2-enes in 65–87% yields. An unusual feature of the reaction is the retention of the triphenylphosphanylidene group in the spiro product.