Enantioselective Organocatalytic Mannich Reaction and Fluorination Sequence of Pyrazolones to Isatin‐derived Ketimines

An efficient asymmetric synthesis of oxindole‐pyrazolone adducts via organocatalytic Mannich reaction of 1‐phenyl‐1H‐pyrazol‐5(4H)‐ones with ketimine derivatives derived from isatins, followed by sequential electrophilic fluorination, has been developed. This approach offers a facile way to prepare chiral 3‐amino‐3‐(4‐fluoropyrazol‐4‐yl)‐substituted oxindole derivatives with a wide range of functional group tolerance.