Glycal

About: Glycal is a research topic. Over the lifetime, 897 publications have been published within this topic receiving 17422 citations.

Synthesis and Glycosidation Reactions of 3-Halo-2,3,6-trideoxy-L-arabino-hexopyranoses

Abstract: Reaction of hydrogen chloride or hydrogen bromide in glacial acetic acid with 3,4-di-O-acetyl-L-rhamnal followed by hydrolysis and acetylation of the reaction product afforded 3-chloro- or 3-bromo-2,3,6-trideoxy-L-arabino-hexopyranoses. These novel halosugars were further converted into various glycosides

Ligand-Controlled Stereoselective Synthesis of 2-Deoxy-β-C-glycosides by Cobalt Catalysis.

Abstract: 2-Deoxy-β-C-glycosides represent an important class of carbohydrates that are present in many bioactive molecules. However, due to the lack of substituents at the C-2 position, the stereoselective synthesis of 2-deoxy-β-C-glycosides is highly challenging. Herein, we report a ligand-controlled stereoselective C-alkyl glycosylation reaction to access 2-deoxy-β-C-alkyl glycosides from readily available glycals and alkyl halides. This method exhibits broad substrate scope and excellent diastereoselectivity under very mild conditions. In addition, unprecedented stereodivergent synthesis of 2-deoxy-C-ribofuranosides is achieved using different chiral bisoxazoline ligands. Mechanistic studies suggest that hydrometallation of the glycal with the bisoxazoline-ligated Co-H species may be the turnover-limiting and stereo-determining step of this transformation.

A New Route to N1-Substituted Uracil Derivatives Using Hypervalent Iodine

Abstract: In continuation of our previous study, oxidative coupling reactions of uracil with allylsilane or enol ethers were examined using diacetoxyiodobenzene. The reaction of persilylated uracil with 3,4-dihydro-2H-pyran in the presence of TMSOTf and PhI(OAc)2 resulted in the formation of a dihydropyranyluracil derivative, although the yield was low. In an extension of the oxidative coupling reaction, a novel glycosylation reaction using glycal derivatives as substrates was also developed. The treatment of persilylated uracil and 3,4-dihydro-2H-pyran with (PhSe)2 and PhI(OAc)2 in the presence of a catalytic amount of TMSOTf gave a 2,3-anti-derivative of 1-(3-phenylselanyltetrahydropyran-2-yl)uracil stereoselectively and in good yield.