Asymmetric Mannich Reaction of Isatin-Based Ketimines with α-Diazomethylphosphonates Catalyzed by Chiral Silver Phosphate

An efficient asymmetric Mannich reaction of isatin-based ketimines with α-diazomethylphosphonates has been developed using a chiral binaphthanol-derived silver phosphate as the catalyst. This reaction allowed the construction of a series of chiral oxindoles bearing a quaternary stereocenter and amino group at the C3 position with up to 95% yields and 99% ee. Those products could be further transformed into promising densely functionalized compounds by merging of the oxindole and β-aminophosphonate.