Molybdenum-Catalyzed Enantioselective Synthesis of Planar-Chiral (η5-Phosphacyclopentadienyl)manganese(I) Complexes and Application in Asymmetric Catalysis

Enantioselective desymmetrization of C-s-symmetric (eta(5)-2,5-dialkenylphogpholyl)(allyldiphenylphosphine)manganese(I) dicarbonyl complexes 1 was realized by molybdenum-catalyzed asymmetric ring closing, metathesis,(ARCM), and the corresponding bridged planar-chiral phosphacymantrene derivatives 2 were obtained in good yields with excellent enantioselectivity. The enantioselectivity of the ARCM reaction Was strongly influenced by the structures of the phospholyl-bound alkenyl groups, and the highest enantioselectivity of up to 99% ee was achieved in the reaction of 1d,e, which possess the 2-inethylpropenyl substituents at the and; of the eta(5)-phoSpholides. Single-enantiomeric planar chiral 2d, which was obtained by the recrystallization of the highly enantiomerically enriched ARCM product, can serve as a Chiral ligand for the palladium-catalyzed asymmetric allylic alkylation to show good enantioselectivity in up to 74% ee.