Construction of Acyclic Quaternary Stereocenters via Mannich-TypeAddition of?,?-DisubstitutedN-tert-Butanesulfinyl Ketimines toIsatin-Derived Ketimines

A Mannich reaction of deprotonated, highly enantioen-riched alpha,alpha-disubstitutedN-tert-butanesulfinyl ketimines with isatin-derived ketimines was developed to prepare 3-amino-3-substitutedoxindoles bearing an acyclic quaternary stereogenic carbon substitutedwith two sterically similar groups. The excellent stereocontrol of thedeprotonation enabled the formation of metalloenamine intermediateswith stereodefined geometry, while the precise facial selectivity of theC-C bond formation allowed the construction of contiguousquaternary and tetrasubstituted stereocenters with excellent stereo-selectivity

Automated summary

A new Mannich reaction was developed to prepare 3-amino-3-substituted oxindoles containing a specific chiral carbon. Excellent stereocontrol was achieved through deprotonation and C-C bond formation, allowing for the construction of contiguous quaternary and tetrasubstituted stereocenters with high stereo-selectivity.