Enantiomerically pure C-2-symmetric diamines and dithioureas as well as a series of monothioureas have been tested as chiral inducers for hydrosilylation of acetophenone with iridium catalysts. Some new N,S-ligands have been synthesized in good yields, one of them bearing four chiral centers. Enantioselectivities with dithioureas are better than the ones observed with analog diamine ligands. Up to 74% e.e. was reached for acetophenone hydrosilylation with a 10-fold excess of ligand versus iridium precursor. (C) 2002 Elsevier Science B.V. All rights reserved.