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

Meijer, Andréas LU and Ellervik, Ulf LU (2002) In Journal of Organic Chemistry 67(21). p.7407-7412
Abstract
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... (More)
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%. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Organic Chemistry
volume
67
issue
21
pages
7407 - 7412
publisher
The American Chemical Society
external identifiers
  • pmid:12375971
  • wos:000178598600030
  • scopus:0037131383
ISSN
1520-6904
DOI
10.1021/jo0262412
language
English
LU publication?
yes
id
8769e900-53a3-4bf3-9e4b-954f8a084d38 (old id 325581)
date added to LUP
2007-11-02 11:46:00
date last changed
2017-01-01 04:48:41
@article{8769e900-53a3-4bf3-9e4b-954f8a084d38,
  abstract     = {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%.},
  author       = {Meijer, Andréas and Ellervik, Ulf},
  issn         = {1520-6904},
  language     = {eng},
  number       = {21},
  pages        = {7407--7412},
  publisher    = {The American Chemical Society},
  series       = {Journal of Organic Chemistry},
  title        = {Study of interhalogens/silver trifluoromethanesulfonate as promoter systems for high-yielding sialylations},
  url          = {http://dx.doi.org/10.1021/jo0262412},
  volume       = {67},
  year         = {2002},
}