Fesulphos-palladium(II) complexes as well-defined catalysts for enantioselective ring opening of meso heterobicyclic alkenes with organozinc reagents

The air-stable and readily available cationic methyl palladium(II) complexes of planar chiral Fesulphos ligands [(Fesulphos)Pd(Me)(PhCN)]X-+(-) are highly efficient catalysts for the alkylative ring opening of oxa- and azabicyclic alkenes with dialkylzinc reagents, showing broad scope with regards to both the bicyclic substrate and the dialkylzinc reagent. Catalyst loading as low as 0.5 mol % is sufficient to achieve good yields and enantioselectivities ranging 94 -> 99% ee in most cases. {Fesulphos = (1-phosphino-2sulfenylferrocene); X- = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate or PF6-].} The origin of the high asymmetric induction has been rationalized by mechanistic studies combining computational calculations and X-ray structural analysis.