Metal-assisted cycloadditions. Part 1. Synthesis of substituted cyclopentane-derivatives obtained from the reactions of (η1-allyl)dicarbonyl(η5-cyclopentadienyl)iron with electron-deficient olefins and acetylenes

Abstract

(η¹-Allyl)dicarbonyl(η⁵-cyclopentadienyl)iron has been treated with various electron-deficient cyano- and alkoxycarbonyl-substituted olefins and dimethyl acetylenedicarboxylate. The resulting cyclopentyl–Fp [Fp = Fe(CO)₂(cyclopentadienyl)] complexes have been subjected to demetallation reactions employing various reagents. Alkoxycarbonyl esters of the substituted cyclopentanes were isolated by oxidative carboxylation with ceric ammonium nitrate, and cyclic and linear products have been obtained with hydrogen chloride by cleavage of the Fe-C bond. N-Bromopyridinium bromide has yielded a mixture of bromocyclopentane derivatives and cyclo-pentenes. β-Hydride abstraction, with trityl tetrafluoroborate, of the complex (12c) has resulted in the formation of diethyl but-3-enylmalonate.