β2, 2 -Amino Acid N-Carboxyanhydrides Relying on Sequential Enantioselective C(4)-Functionalization of Pyrrolidin-2,3-diones and Regioselective Baeyer-Villiger Oxidation.

A catalytic enantioselective entry to β2, 2 -amino acids enabling their direct coupling with nucleophiles is described. The approach is based upon an effective bifunctional Brønsted base catalyzed construction of a quaternary carbon stereocenter at C4 position of pyrrolidin-2,3-diones. Subsequent regioselective Baeyer-Villiger oxidation of the resultant adducts gives β2, 2 -amino acid N-carboxyanhydrides as the reactive species, which can further react with nucleophiles. Following this strategy both, β2, 2 -amino acid derivatives with different functionalities at the newly created stereocenter, and spirocyclic structures can be efficiently prepared.