Oxidative functionalization of aliphatic and aromatic amino acid derivatives with H2O2 catalyzed by a nonheme imine
Barbara Ticconi1, Arianna Colcerasa1, Stefano Di Stefano1
1Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" and Istituto CNR di Metodologie Chimiche (IMC-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" P.le A. Moro 5 I-00185 Rome Italy osvaldo.lanzalunga@uniroma1.it.
Abstract:
The oxidation of a series of N-acetyl amino acid methyl esters with H2O2 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.
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