Chemoenzymatic access to all four enantiopure stereoisomers of 1-ferrocenyl-1,3-butanediol

The kinetic resolution of ferrocenyl aldol 2 was achieved by a lipase-catalyzed esterification in organic solvent. Lipase from Candida antarctica was also found effective in promoting the enantioselective alcoholysis of acetate (±)-3 with n-BuOH. Both enantiomers of 2 were obtained in enantiopure form and subjected to chemical reduction to afford the corresponding syn- and anti-diols. These diols serve as starting materials for the preparation of new ferrocenyl amino alcohols bearing two stereocenters in the side chain.