摘要:
The new chiral diphosphine ligand (R)-(2'-(bis(trifluoromethypphosphino)-1,1'-binaphthy-1-2yl)diphenylphosphine (2), which contains a bis(trilluoromethyl)phosphine group, was prepared in five steps from (R)-BINOL (5). As a key transformation, the unprecedented electrophilic double trifluoromethylation of the primary phosphine 8 was achieved using the hypervalent iodine trifluoromethylation reagent 1-trifluoromethyl-1,2-benziodoxo1-3-(1H)-one (1), derived from o-iodobenzoic acid. The palladium dichloride complex of this ligand (10) shows the P(CF(3))(2) group with a high degree of pyramidalization at the P atom and a relatively short Pd-P bond (2.2230(4) angstrom), both features being indicative of the strong s-character of the phosphorus lone pair.