N-Pentenyl glycosides

Scheme 11.3 Using a C2-protecting group for arming/disarming of an n-pentenyl glycoside for oxonium ion formation.

Building on the observations of Kahne and Takahashi, Chenault and Castro relied on the selective activation of an isopropenyl glycoside donor with TMSOTf, followed by subsequent activation of a second n-pentenyl glycoside with NIS/TESOTf.12 This one-pot glycosylation offers proof of the concept that Fraser-Reid s glycosides can be incorporated into one-pot syntheses. (See Scheme 11.7.)... 

Rodebaugh, R. Joshi, S. Fraser-Reid, B. Geysen, H. M. Polymer-Supported Oligosaccharides via n-Pentenyl Glycosides Methodology for a Carbohydrate Library, J. Org. Chem. 1997, 62, 5660. 

Scheme 5 The n-pentenyl glycoside-based glycosidation method, (E+ = l(collidine)2CI04) [17].

R. Madsen and B. Fraser-Reid, n-Pentenyl glycosides in oligosaccharide synthesis, Modem Methods in Carbohydrate Synthesis (S. H. Khan and R. A. O Neill, eds.), Harwood Academic Publishers, Amsterdam, 1996, Chap. 7. 

D. R. Mootoo, P. Konradsson, U. E. Udodong, and B. Fraser-Reid, Armed and disarmed n-pentenyl glycosides in saccharide couplings leading to oligosaccharides, J Am. Chem. Soc. 770 5583 (1988). 

A. J. Ratcliffe, P. Konradsson, and B. Fraser-Reid, Application of n-pentenyl glycosides in the regio- and stereo- controlled synthesis of a-linked 79-glycopeptides, Carbohydr. Res. 216 323 (1991). 

U. E. Udodong, C. S. Rao, and B. Fraser-Reid, n-Pentenyl glycosides in the efficient assembly of the blood group substance B tetrasaccharide, Tetrahedron 48 4713 (1992). 

Roberts, and R, Madsen, n-Pentenyl glycosides in organic chemistry A contemporary example of serendipity, Synlelt p. 927 (1992). 

Oligosaccharide Synthesis by n-Pentenyl Glycosides 339 Bert Fraser-Reid and Robert Madsen... 

Abbreviations DMF, A,A-dimethylformamide DMT, 4,4 -dimethoxytrityl HPLC, high-pressure liquid chromatography NPG, n-pentenyl glycoside TEA, triethylamine TCA, trichloroacetic acid THF, tetrahydrofuran TMSOTf, trimethysilyl trifluoromethanesulfonate. 

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