Polystyrene-bound cyclo-BINOLs. New heterogeneous ligands for asymmetric catalysis

BINOL and substituted BINOLs, which have been tethered between the 7 and 7′ sites (i.e. ‘cyclo-BINOLs’), can be attached via this linkage to polystyrene resins using a simple acetalization. Efficacy associated with these new ligands is demonstrated in heterogeneous asymmetric catalysis (e.g. aryl alkyl sulfide oxidations, and 1,2-additions of Et2Zn to aryl aldehydes).