Mechanistic studies suggest that the overall SN2' reactivity derives from reversible anti-oxidative addition followed by irreversible reductive elimination, where regio-and enantioselectivities are controlled by energy disparities in competing pathways. Notably, the substituent of the allylic electrophile orients away from the metal center in the transition state of the reductive elimination step, enabling the use of sterically hindered allylic substrates including those containing multiple aryl rings and t Bu-groups.