Palladium-catalysed allylic alkylations and aminations with hetero- and homoannularly bridged bidentate ferrocene ligands

Sets of hetero- and homoannularly bridged ferrocenyl aminophosphine and diphosphine ligands were investigated in palladium-catalysed allylic alkylation and amination reactions ([1-PPh2-2,1′-(α-R-CH(CH2)2)-ferrocene]: (Rc,Rp)-1: R = N(CH3)2; (Rc,Rp)-4: R = PPh2; (Rc,Rp)-5: R = PCy2; ([1-PPh2-2,3-(α-R-CH(CH2)3)-ferrocene]: (Rc,Rp)-2: R = N(CH3)2; (Sc,Rp)-3: R = N(CH3)2; (Sc,Rp)-6: R = PPh2; (Sc,Rp)-7: R = PCy2). Diphenylprop-2-en-1-yl acetate and pent-3-en-2-yl acetate were used as the substrates and dimethyl malonate or benzylamine as the nucleophiles. Catalytic data were analysed and compared to those of PPFA (8) and Josiphos-type (9, 10) ligands ([1-PPh2-2-(α-R-CHCH3)-ferrocene]: (Sc,Rp)-8: R = N(CH3)2; (Sc,Rp)-9: R = PPh2; (Sc,Rp)-10: R = PCy2). Correlations between changes in enantioselectivity or absolute configuration of product and changes in ligand backbones or functional groups were assessed. Cationic palladium(II) diphenylallyl complexes of ligands 1, 4, 5 and 7 were isolated and their conformational behaviour in solution was analysed both as the isolated complexes and under catalytic conditions. The molecular structure of complex 7C (endo syn/syn form) was determined by X-ray diffraction.