Iron‐Catalyzed Transformations of 2‐Chloro‐1,6‐heptadienes

Abstract (Phosphane)iron complexes in the presence of excess trialkylaluminium reagents catalyze various transformations of 2‐chloro‐α,ψ‐dienes, depending on their structure. Most notably, in the cases of simple 2‐chloro‐1,6‐heptadienes, cyclization with transfer of the alkyl group (Me and Et) from the corresponding trialkylaluminium compound was observed to give 2‐alkyl‐1‐methylidenecyclopentanes. Reaction with 2‐chloro‐1,7‐octadiene afforded the product of reductive dehalogenation. In the case of 2‐chloro‐4‐aza‐1,6‐heptadiene a partial or complete hydrogenation of the double bonds was observed depending on the amount of trialkylaluminum reagent used. Interestingly, allyl(2‐chloroallyl)malonate underwent C−C bond cleavage with the loss of an allyl group to give (2‐chloroallyl)malonate. In the presence of ruthenium catalysts only reductive dehalogenation was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)