NIS/AgOTf

Ant -( 1 — 3)-a-L-Rhap-( 1 —>3)-a-L-Rhap-(l —>2)-a-L-Rhap-O-linkers-BSA Glycosyl Chloride, AgOTf, DBMP thiorhamnoside, NIS, AgOTf. Benzoate, acetate, 76... 

Protected thioglycoside 15 was attached to the soluble polymer support via a DOX-linker 16 (Scheme 20.5) using the NIS/AgOTf protocol, followed by acidic hydrolysis of the acetal using acetic acid. Dissacharide 17 was coupled with glycosyl... 

Reagents i, (Ph3P)3RhCI, Bu"Li ii, ROH, NIS, AgOTf, base iii, MeOTf, base... 

In the view of the well-known reaction of thioglycosides with NBS (77-bromosuccinimide), which generates the unstable cationic species 31 in the course of formation of oxocarbenium ion 32 (Fig. 5.8), Konradsson et al. [5]. reported that 77-iodosuccinimide/trifluoromethanesulfonic acid induces the same reactivity with disarmed thioglycosides as substrates. (NIS/AgOTf or NIS/EtsSiOTf also proves to be an excellent source of iodonium ion.)... 

Thus, by treating an armed thioglycosyl donor with a disarmed thioglycosyl donor that has one hydroxyl group free in the presence of NIS/TfOH, NIS/AgOTf, or NIS/EtsSiOTf, they synthesized disaccharides in good yields (Fig. 5.9). 

For thioglycosides with low donor activity, DMTST is less effective than promotion of the glycosylation reaction with the NIS/AgOTf system. DMTST is useful for the reaction of thioglycosides with acceptors containing unsaturation (eq 11). In some cases, acid-sensitive protecting groups (e.g., sUyl ethers) may transfer or be cleaved under reaction conditions that include DMTST. ... 

Scheme 2 Glycosylation of an octopus molecule made by Baker and coworkers - a AcCN, NIS, AgOTf, reflux, 9% b PdlOHlj/C, Hj, 96%.

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