Right or Left - Enantioselective Catalysis. New Ni, Pd and Pt Phosphane Complexes with the Chiral 9-Phenyldeltacyclanyl Substituent

After introducing chirality with the winding columns of baroque altars and snail shells, the enantioselective hydrogenation of dehydroamino acids is described. Then, the enantioselective homo Diels-Alder reaction of norbornadiene with phenylacetylene is presented, which leads to 8-phenyldeltacyclene in almost enantiomerically pure form. Its reaction with 1,2-bisphosphanylbenzene affords P,P,P'-tris(9-phenyldeltacyclan-8-yl)-1,2-bisphosphanylbenzene, a chelate ligand with 3 chiral deltacyclanyl substituents and a PH bond, comprising 24 asymmetric carbon atoms of a given configuration and a stereogenic secondary phosphorus atom. This chelate ligand forms mononuclear, phosphido-bridged dinuclear and - most unusual - trinuclear Ni, Pd and Pt complexes. The trinuclear complexes consisting of three joint square planar units are unique in Ni, Pd and Pt chemistry.