Cu(I)-catalyzed, α-selective, allylic alkylation reactions between phosphorothioate esters and organomagnesium reagents.

Regiocontrol of allylic alkylation reactions involving hard nucleophiles remains a significant challenge and continues to be an active area of research. The lack of general methods in which α-alkylation is favored underscores the need for the development of new processes for achieving this type of selectivity. We report that Cu(I) catalyzes the allylic substitution of phosphorothioate esters with excellent α-regioselectivity, regardless of the nature of the Grignard reagent that is used. To the best of our knowledge, the Cu-catalyzed allylic alkylation of phosphorothioate esters has never been described. We have also developed a simple protocol for inducing high α selectivity starting from secondary allylic halides. This is accomplished by using sodium phosphorothioates as an additive.