Figure 2.

Chemical synthesis of peracetylated N-acyl-ManN derivatives. (A) Reaction sequence including peracylation, cleavage of O-acyl-residues and peracetylation. GC analyses were performed to confirm the synthesized structures to be peracetylated (B) ManNAc, (C) ManNProp, and (D) ManNBut by comparing respective retention times to those of (E) standard substances, which were confirmed by NMR analysis. Further structural verification was performed by ESI-MS analyses of peracetylated (F) ManNAc, (G) ManNProp, and (H) ManNBut registered as sodium adducts ([M+Na]⁺) as well as sodium adducts after the loss of acetic acid. Hydrogen adducts ([M+H]⁺) formed after the loss of acetic acid are marked by trianglels (▼) and unidentified signals are labeled by asterisks (*). Retention times as well as monoisotopic masses are assigned with the first decimal place.