- Zn(OTf)2-catalyzed glycosylation of glycals: Synthesis of 2,3-unsaturated glycosides via a Ferrier reaction
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A mild, catalytic, and efficient protocol has been developed for the synthesis of 2,3-unsaturated glycosides or 'pseudo-glycals' using Zn(OTf) 2. Stereoselective glycosylation of glycal donor with various acceptors comprising of alcohols, phenols, thiols, and sugar aglycones proceeds smoothly to afford the corresponding 2,3-unsaturaed glycosides in good to excellent yields. Georg Thieme Verlag Stuttgart New York.
- Narasimha, Gundeboina,Srinivas, Batthula,Radha Krishna, Palakodety,Kashyap, Sudhir
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- Diastereoselective Synthesis of Thioglycosides via Pd-Catalyzed Allylic Rearrangement
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Stereoselective glycosylation is challenging in carbohydrate chemistry. Herein, stereoselective thioglycosylation of glycals via palladium-catalyzed allylic rearrangement yields various substituents on α-isomer thioglycosides. Two comprehensive series of aryl and benzyl thioglycosides were obtained via a combination of thiosulfates with glycals derived from glucose, arabinose, galactose, and rhamnose. Furthermore, diosgenyl α-l-rhamnoside and isoquercitrin achieved selectivity via stereospecific [2,3]-sigma rearrangements of α-sulfoxide-rhamnoside and α-sulfoxide-glucoside, respectively.
- Jiang, Xuefeng,Li, Jiagen,Wang, Ming
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p. 9053 - 9057
(2021/11/30)
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- Ruthenium Catalyzed Stereo/Chemo/Regioselective One-Pot Synthesis of C(2)-C(3) Unsaturated and α-d-Mannopyranosyl Sulfones
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An efficient and divergent approach to C(2)-C(3) unsaturated glycosyl and α-d-mannopyranosyl sulfones has been developed via ruthenium-promoted direct glycosylation, oxidation, and dihydroxylation from glycal in one-pot. The presence of stoichiometric amounts of NaIO4 and in situ generation of RuO4 from a RuCl3-NaIO4 reagent system were crucial for chemoselective oxidation of sulfide in the presence of an olefin moiety. The dual-role of ruthenium in sequential glycosylation-oxidation-dihydroxylation is amenable to a wide range of thio acceptors to access α-d-mannopyranosyl sulfones in good yields with high regioselectivity.
- Chittela, Sravanthi,Reddy, Thurpu Raghavender,Radha Krishna, Palakodety,Kashyap, Sudhir
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p. 7108 - 7116
(2015/07/28)
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