The nitrogen-based heterocyclic 2-mercapto-6-methylpyridine was selected as a carbohydrate leaving group to determine its role in chemical glycosylation. The pyranose series containing glucose, galactose, and mannose bearing this leaving group was subjected to gylcosidation with the use of thiophilic promoters. Iodine, copper(II) triflate (Cu(OTf)2), and silver(I) triflate (AgOTf) were designated due to their performances in the coupling reation. While the reactivity rates varied widely, copper and silver triflates activated the mercaptopyridine moiety smoothly. Interestingly, iodine displayed little to no reactivity in the coupling reaction. What was discovered, was that the glycosides fit into a convenient one-pot orthogonal glycosylation strategy when coupled with sugars bearing S-ethyl leaving groups. A donor with the mercaptopyridine leaving group was couple with an acceptor containing anomeric S-ethyl in the presence of AgOTf. Upon completion of the first glycosylation, the trisaccharide was achieved by addition of I2 and a new acceptor containing mercaptopyridine. Further development in oligosaccharides strategies are being pursued containing the 2-mercapto-6-methylpyridine leaving group.

6-Methylpyrid-2-yl thio glycosides

255th National Meeting (2018)

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