Amino acids 3-substituted, enantioselective radical

Scheme 43 /S-Substituted a-amino acids via enantioselective radical conjugate additions... 

Allylic hydrogens are replaced by acyloxy groups by reaction of peroxy esters in the presence of catalytic amounts of copper salts, including Cu(OAc)2- The reaction probably proceeds via the formation of an aUylic radical, which reacts quickly with Cu to form a Cu intermediate that generates the most substituted aUcene, probably via a pericyclic transition state (eq 6)T Allylic oxidation can be enantioselective when performed in AcOH and pivalic acid in the presence of Cu(OAc)2 and an L-amino acid. ... 

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