A diastereoselective Mannich-type reaction of α-fluorinated carboxylate esters: synthesis of β-amino acids containing α-quaternary fluorinated carbon centers

We report a diastereoselective Mannich-type reaction of alpha-alkyl, alpha-aryl, and alpha-vinyl fluoroacetates with N-tert-butylsulfinyl imines. This method provides a powerful means to access a broad range of highly functionalized beta-amino acids containing alpha-fluorinated quaternary stereogenic carbon centers. We also show that the stereochemical outcome of the present reaction is highly dependent on the steric and electronic properties of the fluorocarbon nucleophiles. This protocol uses readily available starting materials, tolerates a variety of functional groups, and is operationally simple.