Synthesis and reactivity of acyclic (pentadienyl)iron(1+) cations: model studies for the preparation of the 8E,10Z,16E,18E-tetraene segment of macrolactin A

The dicarbonyl(1,2-dimethylpentadienyl)triphenylphosphineiron(1+) cation (1 1) has been prepared from methyl 4-methyl-2E,4E-hexadienoate in four steps. The cation (11) reacts with hydride and carbon nucleophiles in a regiospec ific fashion to afford (3-methyl-2E,4Z-diene)iron complexes. Dicarbonyl(3-m ethyl-7-nitro-2E,4Z-heptadiene)triphenylphosphineiron (15), the product fro m the reaction of 11 with nitromethane anion, has been utilized as a precur sor for nitrile oxide-olefin cyclocondensations. (C) 1999 Elsevier Science S.A. All rights reserved.