Practical Stereoselective Synthesis of C3‐Spirooxindole‐ and C2‐Spiropseudoindoxyl‐Pyrrolidines via Organocatalyzed Pictet‐Spengler Reaction/Oxidative Rearrangement Sequence

A stereoselective synthetic route to chiral C3‐spirooxindole‐ and C2‐spiropseudoindoxyl‐pyrrolidines was accomplished by an enantioselective organocatalyzed Pictet‐Spengler reaction of tryptamines and isotryptamines followed by a diastereoselective oxidative rearrangement using eco‐friendly oxidants (i. e., NaOCl ⋅ 5H2O and Oxone®). This sequential reaction enables rapid access to chiral C3‐spirooxindole‐ and C2‐spiropseudoindoxyl‐pyrrolidines in a one‐pot process. A Wnt signaling inhibitory assay of the prepared enantioenriched spiro compounds demonstrated that they exhibited moderate activities.