Enantioselective Organocatalyzed Direct α-Thiocyanation of Cyclic β-Ketoesters by N-Thiocyanatophthalimide

A new electrophilic thiocyanation reagent, N-thiocyanatophthalimide, was synthesized and applied to the first example of catalytic asymmetric electrophilic α-thiocyanation of various cyclic β-ketoesters by the bifunctional cinchona alkaloid catalysis. Thus, a variety of chiral α-thiocyanato β-ketoesters with a quaternary carbon center have been achieved in excellent yields (up to 99%) and high enantioselectivities (up to 94% ee) in a convenient manner.