Asparagines rearrangement

Fig. 2. Continued) chain of Cys+i (N-terminal amino acid of the C-extein) on the thioester results in the formation of a branched intermediate. Excision of the intein occurs by peptide bond cleavage coupled to succinimide formation at the C-terminal asparagine of the intein. The ligated exteins undergo a spontaneous S-N acyl rearrangement to create a stable amide bond.

During the late stages of the asymmetric total synthesis of capreomycidine IB it was necessary to transform an asparagine residue into a diaminopropanoic acid residue." R.M. Williams et al. employed a chemoselective Hofmann rearrangement, thereby avoiding protection and deprotection steps that would have been necessary had the diaminopropanoic acid been introduced directly. The complex pentapeptide was treated with FIFA and pyridine in the presence of water to afford the primary amine in high yield. 

Hofmann rearrangement. Primary amides such as protected asparagines are degraded by Phl(OAc)j in one operation. 

Isoaspartyl peptide bond, a peptide bond formed via an intramolecular rearrangement of the peptide backbone of peptides and proteins at amide bonds of asparagine (—> aspartimide, /i-aspartylpeptides). Sensitive peptide bonds such as Asp-Gly sequences are often prone to succin-imide formation and concomitant isoaspartyl peptide shift) formation, especially when treated with strong acids such as HF or TFMSA during peptide synthesis operations. 

Oxazolidin-5-one Intermediates. Several workers have demonstrated the significance of an inframolecular cyclization (Scheme 8) in the Schiff base form of aldosyl-a-amino acids, as an intermediate step of the Amadori rearrangement, which is accompanied by decarboxylation of the amino acid. One important example of the reaction is a pathway for acrylamide formation from D-glucose and L-asparagine in fried foods, such as potatoes. 

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