Reactivity of Tricarbonyl(pentadienyl)iron(1+) Cations: Preparation of an Optically Pure Tricarbonyl(diene)iron Complex via Second-Order Asymmetric Transformation

Summary: Reactions of tricarbonyl(2,4-dimethylpentadienyl)iron(l+) hexafluorophosphate (1) with sodium methoxide/methanol and with phosphines are reported. Use of (S)-neomenthyldiphenylphosphine gives a 3:2 mixture of diastereomers. Slow diffusion-controlled recrystallization of the mixture gives the single, optically pure diastereomer 6a in \u3e80% mass recovery via a second-order asymmetric transformation involving reversible addition of the phosphine. The stereochemistry of 6a at C2 (S) was determined by single-crystal X-ray diffraction analysis