The catalytic enantioselective fluorination of N-H-free 3-substituted oxindoles was accomplished by a Sc(III)/N,N'-dioxide complex. Under mild reaction conditions, a series of 3-aryl- and 3-alkyl-3-fluoro-2-oxindoles were obtained in excellent yields (up to 98%) and enantioselectivities (up to 99% ee) by using N-fluorobisbenzenesulfonimide (NFSI) as the fluorination agent. MaxiPost was synthesized efficiently in 81% yield with 96% ee.
Enantioseletive Fluorination of 3-Functionalized Oxindoles Using Electron-rich Amino Urea Catalyst
An enantioselective fluorination of 3‐functionalized oxindoles using electron‐rich amino urea catalyst is described. Various 3‐functionalized 3‐fluoro‐2‐oxindoles were obtained in good yields and enantio‐selectivity. The resulting enantioenriched 3‐methylene nitrile 3‐fluoro‐2‐oxindole product was found to inhibit indoleamine 2,3‐dioxygenase considerably.