Enantioselective Synthesis of Quaternary α-Amino Acids Enabled by the Versatility of the Phenylselenonyl Group

A novel Cinchona alkaloid-catalyzed enantioselective conjugate addition of alpha-alkyl substituted alpha-nitroacetates to phenyl vinyl selenone was developed. The resulting enantio-enriched alpha,alpha-dialkyl substituted alpha-nitroacetates were subsequently converted to various cyclic and acyclic quaternary alpha-amino acids, taking advantage of the rich functionalities of the resulting Michael adducts. Novel protocols allowing chemoselective reduction of phenyl selenone to phenyl selenide and reduction of alkyl phenyl selenones to alkanes are also reported.