Organoiron complexes of podocarpic acid derivatives

Article abstract of DOI:10.1016/0022-328X(90)87009-3

Treatment of the non-conjugated 1,4-dienes obtained by Birch reduction of podocarpa-8,11,13-trien-19-ol (2) and 12,19-dimethoxypodocarpa-8,11,13-triene (4) with Fe3(CO)12 leads (albeit in low yields) in each case to a mixture of η⁴-1,3-diene iron complexes whose structure have been assigned by NMR spectroscopy.One of these complexes has been successfully converted into a cationic η⁵-dienyl iron salt (35) by treatment with acid.Attempted complexation of the 1,4-dienol ethers by treatment with a variety of sources of Fe(CO)3 under mild conditions has led to the conclusion that prior conversion of a 1,4-dienol ether into a 1,3-dienol ether is necessary for success.In model studies, treatment of 1-methoxy-3,4-dimethylcyclohexa-1,4-diene (9) with Fe3(CO)12 has given η⁴-diene and subsequently η⁵-dienyl iron complexes.