Oxidative functionalization of aliphatic and aromatic amino acid derivatives with H2O2 catalyzed by a nonheme imine based iron complex

摘要

The oxidation of a series of N -acetyl amino acid methyl esters with H _(2) O _(2) catalyzed by a very simple iminopyridine iron( II ) complex 1 easily obtainable in situ by self-assembly of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf) _(2) was investigated. Oxidation of protected aliphatic amino acids occurs at the α-C–H bond exclusively ( N -AcAlaOMe) or in competition with the side-chain functionalization ( N -AcValOMe and N -AcLeuOMe). N -AcProOMe is smoothly and cleanly oxidized with high regioselectivity affording exclusively C-5 oxidation products. Remarkably, complex 1 is also able to catalyze the oxidation of the aromatic N -AcPheOMe. A marked preference for the aromatic ring hydroxylation over Cα–H and benzylic C–H oxidation was observed, leading to the clean formation of tyrosine and its phenolic isomers.