Asymmetric Synthesis of Oxindole-Derived Vicinal Tetrasubstituted Acyclic Amino Acid Derivatives by the Mannich-Type Reaction.
Ke-Qiang HouFeng ZhouXue-Ping ChenYang GeAlbert Sun-Chi ChanXiao-Feng XiongPublished in: The Journal of organic chemistry (2020)
The catalytic asymmetric Mannich-type reaction of 3-hydroxy/3-aminooxindoles with 2-aminoacrylates to afford oxindole-derived acyclic amino acid derivatives bearing vicinal tetrasubstituted stereocenters is reported. (DHQ)2PHAL (4g) and quinine-derived squaramide (4d) were identified as efficient catalysts. Transformations of the Mannich-type reaction products highlight the utility of this synthetic strategy.