Lipase-assisted preparation of enantiopure ferrocenyl sulfides possessing planar chirality and their use in the synthesis of chiral sulfoxides

Racemic 2-hydroxymethyl-1-phenylthioferrocene 5 and 2-hydroxymethyl-1-tert-butylthioferrocene 6 were subjected to kinetic resolution via acetylation catalysed by lipase from Candida antarctica (Novozym® 435) or Mucor miehei (Lipozyme® IM). The obtained enantiopure thioethers underwent chemical oxygenation at the sulfur atom to give the corresponding ferrocenyl sulfoxides with settled central/planar chirality.