Metal-assisted cycloadditions. Part 2. Reactions of dicarbonyl(η5-cyclopentadienyl)(η1-3-methoxyallyl)iron with electron-deficient olefins and acetylenes

Abstract

Dicarbonyl(η⁵-cyclopentadienyl)(η¹-3-methoxyallyl)iron has been treated with ethyl 3,3-dicyanoacrylate, diethyl 1-cyanoethylenedicarboxylate, ethyl 2,3-dicyanoacrylate, diethyl methylenemalonate, and trimethyl ethylenetricarboxylate to yield the corresponding cyclopentyl–Fp derivatives [Fp = Fe(CO)₂(cyclopentadienyl)] as a mixture of diastereoisomers and these have been separated by column chromatography. The Fp-moiety of these cyclopentyl-Fp adducts has been replaced with an alkoxycarbonyl group by treatment with ceric ammonium nitrate. Substituted cyclopentene derivatives have been isolated from the reaction of these Fp-adducts with either hydrogen chloride or trityl tetrafluoroborate.