171. New Synthetic Routes to β-Olefinic Triphenylphosphonium Salts via (Diolefin)tricarbonyliron Complexes

Article abstract of DOI:10.1002/hlca.19830660616

The regio- and stereospecific preparation of β-olefinic triphenylphosphonium salts, starting from (diolefin)tricarbonyliron compounds is described.The latter are converted by various routes into either <(allyl)Fe(CO)4>⁺- or <(dienyl)Fe(CO)3>⁺-derivatives.The allylic cations, when reacted with P(C6H5)3, yield uncomplexed (2-en-1-yl)triphenylphosphonium salts in good yields, while treatment of the dienyl cations with P(C6H5)3 leads to the quantitative formation of (2,4-diene-1-yl)triphenylphosphonium ions still coordinated to the Fe(CO)3-moiety.A method of oxidative decomposition is described, by which the free phosphonium salts can be obtained.All new compounds were characterized by 13C-NMR spectra and also, where necessary, by 1H-NMR decoupling experiments to comfirm the stereochemical assignments.Many of the new phosphonium salts, potentially useful as Wittig reagents for natural product syntheses, are difficult to obtain by convetional unequivocal routes.