872848-25-4Relevant academic research and scientific papers
Optically pure N-hydroxy-O-triisopropylsilyl-α-L-amino acid methyl esters from AlCl3-assisted ring opening of chiral oxaziridines by nitrogen containing nucleophiles
Di Gioia, Maria Luisa,Leggio, Antonella,Le Pera, Adolfo,Liguori, Angelo,Siciliano, Carlo
, p. 10494 - 10501 (2007/10/03)
This article reports a straightforward and unprecedented process of AlCl3-assisted oxaziridine ring opening by nitrogen containing nucleophiles, in a totally anhydrous milieu. Under these conditions, nucleophiles exclusively attack the carbon atom of the three-membered heterocycles, obtained from methyl esters of natural α-amino acids, generating N-hydroxy-α-L-amino acid methyl esters. No nitrones, amides, or other side products, either from unwanted rearrangements or due to the attack of the nucleophile on the N atom of the oxaziridine systems, are formed. The hydroxylamine compounds are recovered in excellent yields, after their site-specific conversion into the corresponding O-triisopropylsilyl derivatives, by exposure to triisopropylsilyl triflate in the presence of 1H-imidazole. Derivatization, performed immediately after the recovery of the N-hydroxylated precursors, allows the chiral integrity of the asymmetric α-carbon atoms in the amino acid methyl esters to be retained. It also protects the obtained compounds from frame degradation by disproportionation. N-Hydroxy-O- triisopropylsilyl-α-L-amino acid methyl esters are important intermediates in the study of natural α-L-amino acid metabolic pathways and are ideal candidates as starting materials in the synthesis of biologically, pharmacologically, and nutritionally important N-hydroxy peptides.
