Showing papers on "Glucal published in 2018"
TL;DR: Results suggest a mechanism whereby conformational and electronic factors determine the partitioning of an intermediate acyl nitrenoid between alkene addition, leading to amidoglycosylation, and C3-H insertion, providing the dihydropyranone byproduct.
Abstract: The rhodium(II)-catalyzed oxidative cyclization of glycal 3-carbamates with in situ incorporation of an alcohol nucleophile at the anomeric position provides access to a range of 2-amino sugars having 1,2-trans-2,3-cis stereochemistry, a structural motif present in compounds of medicinal and biological significance such as the streptothricin group of antibiotics and the Chitinase inhibitor allosamidin. All of the diastereomeric d-glycal 3-carbamates have been investigated, revealing significant differences in anomeric stereoselectivity depending on substrate stereochemistry and protecting groups. In addition, some substrates were prone to forming C3-oxidized dihydropyranone byproducts under the reaction conditions. Allal- and gulal 3-carbamates provided uniformly high stereo- and chemoselectivity, while for glucal substrates, acyclic, electron-withdrawing protecting groups at the 4O and 6O positions were required. Galactal 3-carbamates have been the most challenging substrates; formation of their amidogly...
15 citations
TL;DR: The catalyst CeCl3·7H2O-NaI and ligand L-proline in toluene, was found to be much more efficient and high atom economic for the stereoselective glycosidation of prop argyl alcohol with glucal, afforded exclusively α-2-deoxy propargyl glycoside in 98% optimized yield.
9 citations
TL;DR: A highly efficient stereoselective synthesis of sugar fused 1,2-annulated isochromans is reported by utilizing the oxa-Pictet-Spengler cyclization reaction.
Abstract: A highly efficient stereoselective synthesis of sugar fused 1,2-annulated isochromans is reported by utilizing the oxa-Pictet–Spengler cyclization reaction The process is found to be very general as both glucal and galactal derived C2-hydroxy-α-C-aryl glycosides lead to the target molecules in good yields The utility of this strategy was extended to the synthesis of sugar fused isochromanones, which are bergenin type molecules
4 citations
2 citations
Patent•
15 May 2018
TL;DR: In this article, a synthetic method of acetylated delta-hydroxy-alpha, β-unsaturated furfural is disclosed, in which a glucal having a protective group, an organic solvent and water are mixed according to mole-volume ratio of 1 mol:50-250 L:0.6-2.8 L, a ring-opening reaction is performed by adopting FeCl3 as a catalyst, a product is mixed with triethylamine, DMAP and acetic anhydride according to a molar ratio of1:1-3:0
Abstract: A synthetic method of acetylated delta-hydroxy-alpha,beta-unsaturated furfural is disclosed. The method is characterized in that a glucal having a protective group, an organic solvent and water are mixed according to mole-volume ratio of 1 mol:50-250 L:0.6-2.8 L, a ring-opening reaction is performed by adopting FeCl3 as a catalyst, a product is mixed with triethylamine, DMAP and acetic anhydride according to a molar ratio of 1:1-3:0.1-0.5:0.5-3.0, the mixture is subjected to acetaylation at 0-45 DEG C, and neutralization, extraction and purification are performed after the reaction is finishedto obtain acetylated delta-hydroxy-alpha,beta-unsaturated furfural having different protective groups. Compared with the prior art, the method has characteristics of a simple process, convenient operation, nontoxic and economical agents, mild reaction conditions and a high reaction speed and a high yield, and is a green, economical and efficient novel acetylated Perlin aldehyde synthetic method having a good application prospect.
TL;DR: In this paper, the reaction of 3,4,6,tri-O -acetyl-D-glucal with silver 4-nitrophenolate in the presence of N -iodosuccinimide and N -bromosuccINimide produced (2,6-dihalo-4-nitro)phenyl 2-halo-2-deoxy-α-d-glycopyran.
Abstract: Reaction of 3,4,6-tri-O -acetyl-D-glucal with silver 4-nitrophenolate in the presence of N -iodosuccinimide and N -bromosuccinimide produced (2,6-dihalo-4-nitro)phenyl 2-halo-2-deoxy-α-D-glycopyran...