Dual Catalytic Decarboxylative Allylations of α-Amino Acids and Their Divergent Mechanisms

The room temperature radical decarboxylative allylation of N‐protected α‐amino acids and esters has been accomplished via a combination of palladium and photoredox catalysis to provide homoallylic amines. Mechanistic investigations revealed that the stability of the α‐amino radical, which is formed by decarboxylation, dictates the predominant reaction pathway between competing mechanisms. A direct method for the decarboxylative allylation of α‐amino acid derivatives using dual palladium and photoredox catalysis (see scheme) to circumvent traditional limitations in decarboxylative couplings has been developed. The coupling is site‐specific for the position that bears CO2, allowing the kinetic formation of contra‐thermodynamic radical species.