An approach to the synthesis of aldosyl phosphates via aldosyl phosphites

✍ Scribed by Tomoya Ogawa; Akinori Seta

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 264 KB
• Volume: 110
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(82)85040-4

✦ Synopsis

Phosphates linked to anomeric carbon atoms have been reported to be present at the cell surface of such microbes as Staphylococcus lactis2, Saccharomyces cerevisiae3, Micrococcus lysodeikticufl , and Streptococcus pneumoniae' , and to be a part of the structure of glycan chains of glycoproteins' . The lipid A moiety of LPS also contains glycosyl phosphate units'.

In 1976, Letsinger and Lunsford* reported a new synthetic approach to oligonucleotides via phosphorous triester intermediates. As part of a project on studies of the synthesis of oligosaccharides, we report here an approach to the synthesis of aldosyl phosphates through the intermediacy of aldosyl phosphites. A general synthetic sequence is depicted in Scheme 1. An anomeric hydroxyl group (1) reacts with trivalent phosphorus chloride to give the anomeric phosphorochloridite (2), which then reacts with another hydroxyl group to give the phosphorous triester 3, and oxidation of 3 leads to formation of the aldosyl phosphoric triester 4. From the point of view of synthesis, this approach would be expected to be efficient, owing to the high reactivity of phosphorochloridite as a phosphorylating reagent.

First, we describe an efficient synthesis of aldosyl phosphites using phosphorus trichloride as the phosphorylating agent. Treatment of 2,3,4,6-tetrad-acetyl-D-glucose (5) with PCl, in oxolane (THF) in the presence of iPrzNEt at -78' gave 6, which was hydrolyzed to give' a 53% yield of 7. [a]D +86.2' (c 2.50, CHCl,)?; RF 0.65 in 10:5: 1 CHC13-MeOH-HzOtt . *Synthetic Studies on CeILSurface Glycans, Part XXI. For Part XX, see ref. 1. **To whom enquiries should be addressed. tCompounds with [ar] D recorded gave satisfactory elemental analyses. ttPhosphoru,containIng compounds were detected on t.1.c. plates by using the specific spray reported by Dittmer and Lester'.