Preparation of Chiral-at-Iron-Substituted Allyl and Vinyl Sulfones. Subsequent Enolate Generation and Stereo- and Regioselective Alkylation

Abstract

The (η5-cyclopentadienyl)Fe(CO)2 (Fp) anion adds to allenic sulfone (CH2CCHSO2Ph) 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 α: γ alkylation changes dramatically as the electrophile structure changes.