Ring opening of sialyllactones with glycine esters: Synthesis of selectively protected glycinyl-NeuAc saccharopeptides

The first synthesis of N-acetylneuraminic acid 1,7-lactone

“…In our work, we did not consider the direct lactonization of Neu5Ac 1 by means of N,N-dicyclohexylcarbodiimide (DCC) in pyridine since it was reported that, in these conditions, a partial 1,4-intramolecular lactonization of Neu5Ac 1 occurs to afford a mixture of the bicyclic 1,4lactone 9,10 5a and of the starting Neu5Ac 1. We excluded also the lactonization mediated by usual acylic chlorides or anhydrides on the basis of the extensive work of Ogura and coworkers [11][12][13] and of Gervay et al 8,14,15 who reported the formation of a variety of peracylated and partially acylated 1,7-lactones 4b and 4c, and of peracylated 1,4-lactones 5b. Also some preliminary attempts to perform a direct chemoselective 1,7-lactonization of Neu5Ac 1, under catalysis of protic and aprotic acids, performed in our laboratory, were unsuccessful.…”

Solid Phase Synthesis and Secondary Structural Studies of (1→5) Amide-Linked Sialooligomers1

“…We reasoned that the pendent side chain of NeuAc would afford greater solubility and thus began synthetic studies on the preparation of functionalized sialic acids for incorporation into amide-linked oligomers. Several analogues of NeuAc, capable of undergoing solution phase amidation, were prepared, but the coupling yields were disappointingly low . Therefore we decided to explore solid-phase methods in order to improve efficiency.…”

Pyranosyl Sugar Amino Acid Conjugates: Their Biological Origins, Synthetic Preparations, and Structural Characterization

“…Sabesan nicely illustrated this point in his work on amide-linked disaccharides containing NeuAc. [47] Both five-and six-membered lactones were reacted, anticipating that the ring strain in the 1,4-lactones would promote the reaction. This compound was designed to be an isostere of the naturally occurring a-D-NeuAc-(2-6)b-D-Gal glycosidic linkage ( Figure 25).…”