Synthesis, Molecular Structure, and Catalytic Evaluation of Centrostereogenic Ferrocenophane Phosphines
Abstract
1,1'-[(1R)-1-Diarylphosphino-1,3-propanediyl]ferrocenes, where aryl = phenyl, 2-tolyl, 4-tolyl, mesityl, 4-anisyl, 4-(trifluoromethyl)phenyl, were prepared as new chiral ferrocenophane phosphines featuring only central chirality in good yields by the reaction of the corresponding chiral alcohol, 1,1'-[(1R)-1-hydroxy-1,3-propanediyl]ferrocene, and diarylphosphines in the presence of chlorotrimethylsilane and sodium iodide. These phosphines were studied as ligands in palladium(II) complexes and further evaluated in two mechanistically different model catalytic reactions, namely in Pd-catalyzed asymmetric allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate, and in enantioselective aza-Morita-Baylis-Hillman reactions of aromatic N-sulfonyl imines with methyl vinyl ketone.