Preparation of chiral-at-iron-substituted allyl and vinyl sulfones. Subsequent enolate generation and stereo- and regioselective alkylation

The (eta(5)-cyclopentadienyl)Fe(CO)(2) (Fp) anion adds to allenic sulfone (CH2=C=CHSO2Ph) to generate predominantly iron-substituted allyl or vinyl sulfones, depending on. the reaction conditions chosen. Following a phosphine for CO ligand substitution, these allyl or vinyl sulfones can, be deprotonated to yield carbanions, which can be alkylated regio-and stereoselectively. These alkylation reactions are unusual for allyl sulfones in that the ratio of alpha:gamma alkylation changes dramatically as the electrophile structure changes.