Synthesis of S-Glycosyl Xanthates by Phase Transfer Catalyzed Substitution of Glycosyl Halides |
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Authors: | Francęois D. Tropper Fredrik O. Andersson Suoding Cao René Roy |
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Affiliation: | Department of Chemistry , University of Ottawa Ottawa , Ontario, Canada , KIN 6N5 |
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Abstract: | Abstract Peracetylated glycosyl- and glycobiosyl bromides and chlorides 1-4 including acetochloroneuraminic acid 5 were stereoselectively transformed into their corresponding S-glycosyl xanthates 6-10 in high yield (91-98%) under phase transfer catalyzed conditions. The reactions occurred at room temperature using tetrabutylammonium hydrogen sulfate as the catalyst. The substitutions gave complete inversion of configuration and thus proceeded by an SN2 type mechanism. Changing the organic solvent from methylene chloride to ethyl acetate had no detrimental effect on the outcome of the reactions but avoided an undesirable side reaction between the xanthate anion and methylene chloride. |
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