Photochemistry of aminoketones, XII. The behaviour of N-acylglycinate rotamers in the photochemical glycine ? proline conversion

Free-Radical Reactions in the Synthesis of α-Amino Acids and Derivatives

“…The reactions of the radicals 171a and 171b were studied as a model for reactions catalyzed by the enzyme pyruvate formate-lyase . The photochemically induced cyclization of the N -(benzoylethyl)glycine derivatives 174 occurred diastereoselectively, in this case via 1,6-hydrogen atom transfer (Scheme ). , Similar products were obtained from reactions of derivatives of alanine and phenylglycine . More recently, reactions of analogous C 2 -symmetric pyrrolidine derivatives have been found to occur with a high degree of stereocontrol, as illustrated in the reaction of the glycinamide 175 to give only the stereoisomer 176 (Scheme ) …”