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Study of interhalogens/silver trifluoromethanesulfonate as promoter systems for high-yielding sialylations

In English

Författare

Summary, in English

We have studied interhalogen/silver trifluoromethanesulfonate (IX/AgOTf) promoted glycosylations and found differences in the sensitivity of the formed oxocarbenium ions (e.g. from compounds with or without participating groups) toward halide nucleophiles. These differences can be explained using the HSAB theory. By applying this theory on sialylations, we increased the yield for a model reaction from a highly unpredictable 35-46% using ICl to 74% using IBr. We have also showed that the most prominent role of the silver ions is lowering the concentration of the halide nucleophile rather than activating the interhalogen compound and, by increasing the amount of AgOTf from 1 to 1.5 equiv (with respect to IBr), the yield in the model reaction improved from 74% to 89%. A comparison of two different anomeric leaving groups showed that glycal formation can be minimized using a thiophenyl donor instead of xanthate. By combining these observations, we were able to increase the yield of the model reaction to 97%.

Publiceringsår

2002

Språk

Engelska

Sidor

7407-7412

Publikation/Tidskrift/Serie

Journal of Organic Chemistry

Volym

67

Issue

21

Dokumenttyp

Artikel i tidskrift

Förlag

The American Chemical Society (ACS)

Ämne

  • Organic Chemistry

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1520-6904