Asymmetric Synthesis of Novel Ferrocenyl Ligands with Planar and Central Chirality.
A stereogenic center at the position beta to the metallocene backbone is present in ferrocenyl ligands 2, which are interesting for asymmetric catalysis. These planar-chiral compounds are accessible for the first time by a highly diastereoselective and enantioselective synthesis (de=93-97 %; ee>/=96 %) from the ferrocenyl ketones 1. A variety of donor groups (E(1)=Ph(2)P small middle dotBH(3), SMe, SiPr; E(2)=SMe, STol, SePh, Ph(2)P small middle dotBH(3), iPr(2)P small middle dotBH(3)) can be introduced as electrophiles. Tol=tolyl=CH(3)C(6)H(4).
Enders
D
Institut für Organische Chemie der RWTH Aachen, Professor-Pirlet-Strasse 1, D-52074 Aachen (Germany).
Peters
R
Lochtman
R
Raabe
G