Synthesis of indene derivatives via electrophilic cyclization.

3-Iodo-1H-indene derivatives are synthesized by iodonium-promoted 5-endo-dig carbocyclization of 2-substituted ethynylmalonates. Various 2-substituted ethynylmalonates bearing aryl-, alkyl- and ether-protected propargyl alcohols were successfully converted to cyclized products. Their use in subsequent reactions as substrate and catalyst was investigated.