Methylsulfenyl Trifluoromethanesulfonate

[59259-48-2]  · C2H3F3O3S2  · Methylsulfenyl Trifluoromethanesulfonate  · (MW 196.19)

(activator for formation of glycosidic linkages)

Solubility: prepared and used in 1,2-dichloroethane,1 acetonitrile, or CH2Cl2.1,2

Form Supplied in: prepared and utilized in situ; no characterization is reported and the compound is not commercially available from the main chemical suppliers.

Preparative Methods: prepared by injecting methylsulfenyl bromide into a light-protected flask containing Silver(I) Trifluoromethanesulfonate dispersed in dry 1,2-dichloroethane. The resulting supernatant liquid is removed by syringe from the precipitated solids and utilized immediately. Alternatively, the reagent may be generated in situ by addition of methanesulfenyl bromide to a mixture of substrates and silver triflate in the presence of powdered 4Å molecular sieves.

Methylsulfenyl trifluoromethanesulfonate (1) is an activator in the thioglycoside-mediated formation of glycosidic linkages.1-4 (1) mediates 1,2-trans glycosidation of thioglycosides (2) (eq 1) by providing a superior source of the sulfenyl cation; in the absence of silver triflate, sulfenyl bromides are not glycosidation mediators.1

Sialosides may be prepared efficiently using (1) (eq 2).3,4 The high reactivity of (1) allows reaction at low temperature, which is essential to minimize side reactions. Trisaccharides may also be prepared in high yield by a similar method.5 In these reactions, the use of a hindered amine base (such as Diisopropylamine) prevents the formation of methylthioacetamides.

The same amine-modified activation process allows preparation of intermediates (3) crucial to the synthesis of highly complex ganglioside lactones such as GM3 (eq 3).6

1. Dasgupta, F.; Garegg, P. J. Carbohydr. Res. 1988, 177, C13.
2. Dasgupta, F.; Garegg, P. J. Carbohydr. Res. 1990, 202, 225.
3. Birberg, W.; Löhn, H. TL 1991, 32, 7453.
4. Birberg, W.; Löhn, H. TL 1991, 32, 7457.
5. Löhn, H.; Stenvall, K. TL 1992, 33, 115.
6. Ray, A. K.; Nilsson, U.; Magnusson, G. JACS 1992, 114, 2256.

Joseph Sweeney

University of Bristol, UK

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.