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 alpha-amino acids, generating N-hydroxy-alpha-(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 P-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 (x-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-alpha-(L)-amino acid methyl esters are important intermediates in the study of natural alpha-(L)-amino acid metabolic pathways and are ideal candidates as starting materials in the synthesis of biologically, pharmacologically, and nutritionally important N-hydroxy peptides.
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|Titolo:||Optically pure N-hydroxy-O-triisopropylsilyl-alpha-L-amino acid methyl esters from AlCl3-assisted ring opening of chiral oxaziridines by nitrogen containing nucleophiles|
|Data di pubblicazione:||2005|
|Citazione:||Optically pure N-hydroxy-O-triisopropylsilyl-alpha-L-amino acid methyl esters from AlCl3-assisted ring opening of chiral oxaziridines by nitrogen containing nucleophiles / DI GIOIA M., L; Leggio, Antonella; LE PERA, A; Liguori, A; Siciliano, Carlo. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 70(2005), pp. 10494-10501.|
|Appare nelle tipologie:||1.1 Articolo in rivista|