Synthesis of a trans-chelating chiral diphosphine ligand with only planar chirality and its application to asymmetric hydrosilylation of ketones

Optically active diphosphine (S,S)-2,2 "-bis[(diethylphosphino)methyl]-1,1 "-biferrocene (abbreviated to (S,S)-EtTRAP-H) was synthesized from ferrocen yloxazoline derived from L-valinol in 47% overall yield. The new chiral lig and, (S,S)-EtTRAP-H, which coordinates to a rhodium atom in a trans-chelati ng manner, was effective for asymmetric hydrosilylation of ketones to give optically active secondary alcohols with up to 94% ee. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.