Aryl ferrophites - A new class of ligands for asymmetric catalysis

Enantiopure lithiated 1,2-ferrocenes, [CpFe{1,2-eta(5)-C5H3(Ar)-(Li)}] (Ar = Ph, 4-CF3C6H4, 1-C10H7) react readily with PhOP(OR)(2) to yield [CpFe{1,2-eta(5)-C5H3(Ar)P(OR)(2)}] (R = Ph, 1, 1'-biphenyl-based, 1, 1'-binaphthyl-based) efficiently. Traditional routes to these species, involving the use of chlorophosphites CIP(OR)(2) were found to be ineffective. These ferrophite ligands have been characterised by X-ray crystallography (4 examples) and shown to be effective in both nickel-catalysed addition of AlMe3 to PhCHO (up to 77% ee) and copper(I)-catalysed additions of organoaluminium reagents to enones (up to 92% ee).