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Gin, David Y. Boebel, Timothy A. 2015-09-25T22:13:21Z 2015-09-25T22:13:21Z 10000-01-01 2005 2005 A sulfoxide-catalyzed dehydrative glycosylation for the coupling of carbohydrate hemiacetals and nucleophilic alcohols has been developed. In this procedure, a glycosyl hemiacetal is treated with the reagent combination of benzenesulfonic anhydride and a substoichiometric amount of n-butyl sulfoxide, followed by the addition of an appropriate nucleophilic acceptor to provide for the formation of new anomeric linkages. Mechanistic studies focused on the hemiacetal activation process show that this transformation proceeds through the intermediacy of a glycosyl sulfonate species, which serves as resting state prior to the addition of an external nucleophile and glycosidic bond formation. Successful determination of the proportion of 18O-incorporation in the glycosyl sulfonate as a function of its formation, via the technique of dynamic monitoring of 13C-16/18O isotopic chemical shift perturbations, provides strong evidence that hemiacetal activation proceeds through initial nucleophilic addition of the hemiacetal hydroxyl to the S(IV)-center of a putative sulfonium sulfonate intermediate. Further confirmation for this mechanistic pathway was obtained through the independent synthesis, structure verification, and 1H NMR detection of a glycosyl oxosulfonium species during the sulfoxide-catalyzed conversion of a glycosyl hemiacetal to a glycosyl sulfonate. Made available in DSpace on 2015-09-25T22:13:21Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3198929.pdf: 4524956 bytes, checksum: de4057d2f76ebe926873a54902db9ab8 (MD5) Previous issue date: 2005 Embargo set by: Seth Robbins for item 85462 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 220 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005. http://hdl.handle.net/2142/84181 (MiAaPQ)AAI3198929 eng Chemistry, Biochemistry Sulfoxide Catalyzed Dehydrative Glycosylation. Reaction Development and Mechanistic Analysis text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.