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

Two different classes of sialyllactones were prepared as potential substrates for ring opening reactions with naturally occurring amino acids. The sialyllactones underwent reaction with Glycine ethyl ester hydrochloride salt to afford selectively protected glycine-NeuAc adducts. The reactions could be performed on NeuAc derivatives capable of serving as glycosylation donors. These compounds represent a new class of saccharopeptides, composed of sugar amino acids and naturally occurring amino acids.