Synthesis of novel amino-acid-derived sulfinamides and their evaluation as ligands for the enantioselective transfer hydrogenation of ketones

Novel chiral mono-sulfinyl diamines bearing a stereogenic sulfur atom were prepared in moderate to good yields starting from amino acids by means of a reductive amination of the corresponding amino aldehydes. Their potential as ligands for asymmetric catalysis was evaluated in the metal-catalyzed enantioselective transfer hydrogenation of alkylaryl ketones. The catalysts were generated in situ from sulfinamides 1a-i and arene complexes of rhodium and ruthenium, and the catalytic reductions led to the formation of chiral alcohols with up to 91% ee. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).