409320-13-4Relevant articles and documents
Nitroxyl peptides as catalysts of enantioselective oxidations
Formaggio, Fernando,Bonchio, Marcella,Crisma, Marco,Peggion, Cristina,Mezzato, Stefano,Polese, Alessandra,Barazza, Alessandra,Antonello, Sabrina,Maran, Flavio,Broxterman, Quirinus B.,Kaptein, Bernard,Kamphuis, Johan,Vitale, Rosa Maria,Saviano, Michele,Benedetti, Ettore,Toniolo, Claudio
, p. 84 - 93 (2007/10/03)
The achiral, nitroxyl-containing α-amino acid TOAC (TOAC = 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid), in combination with the chiral α-amino acid Cα-methyl valine [(αMe)Val], was used to prepare short peptides (from di- to hexa-) that induced the enantioselective oxidation of racemic 1-phenylethanol to acetophenone. The best catalyst was an Nα-acylated dipeptide alkylamide with the -TOAC-(αMe)Val- sequence folded in a stable, intramolecularly hydrogen-bonded β-turn conformation with large, lipophilic (hydrophobic) N- and C-terminal blocking groups. We rationalized our findings by proposing models for the diastereomeric intermediates between (R)-[and (S)]-1-phenylethanol and the catalyst Fmoc-TOAC-L(αMe)Val-NHiPr, based on the X-ray diffraction structure of the latter.