Catalytic iron-mediated ene carbocyclizations: Formal [4+4]-ene reactions of triene esters

Article abstract of DOI:10.1016/S0040-4020(01)87749-8

2-Substituted-2,7,9-decatrienoates undergo an iron-catalyzed carbocyclization to yield trans-disubstituted cyclopentanes in moderate-to-good chemical yields. The cyclization products are formally the result of a [4+4]-ene reaction in which cis-propenyl and 2-acroyl functionalities are introduced as appendages to the newly formed cyclopentane ring by the cyclization. Triene ester substrates bearing an alkyl substituent at the 4- or 6-positions cyclize with high 1,2-stereoinduction to yield trisubstituted cyclopentanes in which the relative stereochemistry between three contiguous stereocenters is controlled.