Hydrolysis of the GlcNAc oxazoline: deamidation and acyl rearrangement

Article abstract of DOI:10.1016/0008-6215(95)00222-F

The specific deamidation of 2-acetamido-1,3,4,6-tetra-O-acetyl-α-D-glucopyranose is achieved by p-toluenesulfonic acid-promoted hydrolysis of 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-glucopyrano)-<2,1-d>-2-oxazoline 2 to give quantitative formation of the 1,3,4,6-tetra-O-actyl-2-amino-2-deoxy-α-D-glucopyranose p-toluenosulfonate (5d).This two-step procedure provides an amino sugar which may be readily acylated to give novel glycoconjugates.Altermatively, base-catalyzed O-1 --> N-2 acyl rearrangemet of the amino tosylate 5d gives the 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranose 4 as a 9:1 mixture of α and β anomers.Thus, hydrolysis of GlcNAc oxazoline 2 gives the amino-ester 5 as the kinetic product and the amido-alcohol 4 as the thermodynamic product.Keywords: GlcNAc oxazoline; Deamidation; Acyl rearrangement