N-benzoyl-2-methylalanine (H2L1) is ortho-hydroxylated stereoselectively by trimethylamine N-oxide (TMAO) in the presence of copper (II). The experimental structure of [Cu (L1)(TMAO) 2] suggests that the oxygen transfer agent TMAO transfers the oxygen atom to copper (II), and (L1) 2−, coordinated to copper (II) by a carboxylate oxygen and the amide nitrogen donor, is well pre-organized for an oxygen transfer from copper to the ortho carbon atom ...