title: Exploration of the Oxazolidinthione Protecting System for the Synthesis of Sialic Acid Glycosides.
abstract: An N-acetyl oxazolidinthione protected sialyl thioglycoside was synthesized and its use as a sialyl donor studied. The strongly electron-withdrawing nature of the oxazolidinthione moiety is such that activation could not be achieved at -78 °C. Couplings were therefore conducted at the lowest convenient temperature (-50 °C). Glycosides were formed in good yield but in two out three cases studied selectivities were lower than those seen with the corresponding N-acetyl oxazoldinone protected donor. The resulting N-acetyl oxazolidinthione protectd disaccharides were converted to the corresponding N-acetyl oxazolidinones by treatment with N-iodosuccinimide and triflic acid in the presence of water at 0 °C.
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA.
authors.forename: Salla
authors.initials: S
authors.lastname: Rajender
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA.
authors.forename: David
authors.initials: D
authors.lastname: Crich
keywords: glycosylation; isothiocyanate; oxazolidinthione; ozazolidinone; sialic acid; stereoselectivity