1233979-01-5Relevant academic research and scientific papers
Glycal Metallanitrenes for 2-Amino Sugar Synthesis: Amidoglycosylation of Gulal-, Allal-, Glucal-, and Galactal 3-Carbamates
Buttar, Simran,Caine, Julia,Goné, Evelyne,Harris, Reneé,Gillman, Jennifer,Atienza, Roxanne,Gupta, Ritu,Sogi, Kimberly M.,Jain, Lauren,Abascal, Nadia C.,Levine, Yetta,Repka, Lindsay M.,Rojas, Christian M.
, p. 8054 - 8080 (2018/08/10)
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 amidoglycosylation products is most effective with an electron-withdrawing 6O-Ts substituent and a sterically demanding 4O-TBS group. These 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. Along the amidoglycosylation pathway, high anomeric selectivity results when a glycosyl aziridine intermediate is favored over an aziridine-opened oxocarbenium donor.
Highly stereoselective synthesis of 2,3-unsaturated thioglycopyranosides employing molecular iodine
Reddy, Basi V. Subba,Divyavani,Yadav, Jhillu S.
experimental part, p. 1617 - 1620 (2010/06/20)
Molecular iodine has been utilized for the first time for the thioglycosidation of d-glycals with various thiols to afford the corresponding 2,3-unsaturated thioglycosides in high yields. In the case of tri-O-acetyl-d-glucal, the -anomer was obtained exclusively. The use of readily available iodine makes this method quite simple, more convenient, and practical. Georg Thieme Verlag Stuttgart.
The use of ultrastable y zeolites in the Ferrier rearrangement of acetylated and benzylated glycals
Levecque, Pieter,Gammon, David W.,Jacobs, Pierre,De Vos, Dirk,Sels, Bert
experimental part, p. 828 - 835 (2010/09/08)
The Ferrier rearrangement of a selection of protected glycals was successfully performed using a commercially available H-USY zeolite CBV-720 as catalyst, selected after screening a range of similar catalysts. By incorporating either alcohols, thiophenol, trimethylsilyl azide or allyltrimethylsilane in the reaction it was shown that a range of O-, S-, N- and C-glycosides could be formed. With benzylated glucal and galactal in particular, use of the CBV-720 catalyst led to significantly higher yields of the 2,3-dehydroglycosides than previously reported.
