Topic
Glycal
About: Glycal is a research topic. Over the lifetime, 897 publications have been published within this topic receiving 17422 citations.
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TL;DR: The mild, Lewis-acidic complexes [Mo(CO 4 Br 2 ] 2, (MeCN) 2 Mo(CO) 3 (SnCl 3 )Cl, and (acac) 2 O(OTf) 2 have been found to catalyze the C(1)-specific C -glycosylation reaction of glycal acetates 1 - 3 with silyl enol ethers 4a - 4c and electron-rich aromatics 5a, 5b (PhOMe, PhOH) as mentioned in this paper.
Abstract: The mild, Lewis-acidic complexes [Mo(CO) 4 Br 2 ] 2 , (MeCN) 2 Mo(CO) 3 (SnCl 3 )Cl, and (acac) 2 Mo(OTf) 2 have been found to catalyze the C(1)-specific C -glycosylation reaction of glycal acetates 1 - 3 with silyl enol ethers 4a - 4c and electron-rich aromatics 5a , 5b (PhOMe, PhOH). While silyl enol ethers produce predominantly α- C -glycopyranosides (with 2 : 1 to 4 : 1 selectivity), aromatics tend to afford mainly β- C -glycopyranosides (2 : 1 to 3 : 1) in a thermodynamically controlled process.
11 citations
TL;DR: A variety of unnatural 3-aminodeoxy sugars are synthesized via diversified functionalization of a common glycal intermediate bearing a cyclic sulfamidate ketimine moiety through α-selective glycosylation reactions and the structural modification of diosgenin was investigated.
Abstract: Attachment of various 3-aminodeoxy sugars to natural products or drugs is a prominent method for new drug development. However, access to structurally diversified 3-aminodeoxy sugars and glycosylation with aglycons are challenging. We synthesized a variety of unnatural 3-aminodeoxy sugars via diversified functionalization of a common glycal intermediate bearing a cyclic sulfamidate ketimine moiety. Based on these results, the α-selective glycosylation reactions of these 3-aminodeoxy sugars and the structural modification of diosgenin were further investigated.
11 citations
TL;DR: Transformation of 3- C-branched mono- and di-3-deoxy-d- manno-oct-2-ulosonic acid (Kdo) enyne analogues by asymmetric hydrogenation and saponification provided 2- deoxy-β-carboxyl Kdo analogues in a stereocontrolled mode.
Abstract: A highly efficient approach for the synthesis of 3-C-branched mono- and di-3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) enyne analogues is developed for the first time based on Sonogashira coupling of terminal alkynes with 3-iodo Kdo glycal obtained by the NIS/TMSOTf-promoted one-step reaction from peracetylated Kdo ethyl ester. Further transformation of 3-C-branched mono- and di-Kdo enyne analogues by asymmetric hydrogenation and saponification provided 2-deoxy-β-carboxyl Kdo analogues in a stereocontrolled mode.
11 citations
TL;DR: In this article, a novel chemoenzymatic method for the preparation of glucal 4 in high yield is presented, which helps to gain further insight into the mechanism of the well-documented hypervalent iodine-promoted allylic oxidation of cyclic enol ethers.
Abstract: The reaction of 3,4-bis(O-tert-butyldimethylsilyl)-6-O-tosyl-D-glucal 4 with the Koser reagent [PhI(OH)OTs] unexpectedly afforded tetrahydrofurfural 6 as well as 2,3-anhydropyranose 7 as major products. This unprecedented, stereoselective transformation helps to gain further insight into the mechanism of the well-documented hypervalent iodine-promoted allylic oxidation of cyclic enol ethers. A novel chemoenzymatic method for the preparation of glucal 4 in high yield is presented.
11 citations
TL;DR: A new and efficient method for the facile synthesis of C-2 branched carbohydrates has been developed using an intramolecular radical cyclization fragmentation reaction and an unexpected furanoside was obtained from a tributyltin iodide-promoted rearrangement of the radical intermediate.
11 citations