RIGHT OR LEFT - THIS IS THE QUESTION (ENANTIOSELECTIVE CATALYSIS WITH TRANSITION-METAL COMPOUNDS)

New methods to prepare optically active phosphines for enantioselective transition metal catalysts are presented. The transfer hydrogenation of itaconic acid to give methylsuccinic acid using HCOOH is optimized to optical purity. The enantioselective monophenylation of meso-diols with Cu(0Ac)2/pyridineoxazoline catalysts is introduced as a new reaction. The stereochemistry of the stoichiometric cyclopropanation of styrene with the carbene ligand of a Fe complex is determined by the metal configuration, the optically active phosphine ligand making only a small contribution. Similarly, in the Khand-Pauson reaction of phenylacetylene with norbornene to give optically pure 3a,4,5,6,7,7a-hexahydro-2-phenyl-4,7-methano-1H-indene-1-one, the stereochemistry is determined by the cluster configuration and not by the optically active phosphine ligand. The conclusion is drawn that a control of the metal configuration during enantioselective catalysis would be of major importance for the optical induction. © 1990, IUPAC.