Palladium-Catalyzed α-Arylation of Azlactones to Form Quaternary Amino Acid Derivatives

[reaction: see text] The synthesis of alpha-aryl-alpha-alkyl amino acid derivatives from alpha-amino acids by the arylation of azlactone derivatives is reported. Arylation of azlactones derived from alanine, valine, phenalanine, phenyl glycine, and leucine all provided good yields of the arylated product. Mechanistic studies of this reaction revealed that a stable complex containing a ligand formed by reaction of dba with the azlactone accounts for a new inhibiting effect of dba when reactions are initiated with Pd(dba)(2).