A heterogeneous Pd–Bi/C catalyst in the synthesis of l-lyxose and l-ribose from naturally occurring d-sugars

Abstract

A critical step in the synthesis of the rare sugars, L-lyxose and L-ribose, from the corresponding D-sugars is the oxidation to the lactone. Instead of conventional oxidizing agents like bromine or pyridinium dichromate, it was found that a heterogeneous catalyst, Pd-Bi/C, could be used for the direct oxidation with molecular oxygen. The composition of the catalyst was optimized and the best results were obtained with 5 : 1 atomic ratio of Pd : Bi. The overall yields of the five-step procedure to L-ribose and L-lyxose were 47% and 50%, respectively. The synthetic procedure is advantageous from the viewpoint of overall yield, reduced number of steps, and mild reaction conditions. Furthermore, the heterogeneous oxidation catalyst can be easily separated from the reaction mixture and reused with no loss of activity.

Organobismuth(III) and Dibismuthine Complexes Bearing N,N′-Disubstituted 1,8-Diaminonaphthalene Ligand: Synthesis, Structure, and Reactivity

“…Bismuth compounds are attracting increasing attention due to their application in heterogeneous catalysis, catalysts for organic synthesis, superconducting materials, and also biological activity . Bismuth amides have been used as precursors for metal–organic chemical vapor deposition (MOCVD) of bismuth-containing thin films due to their low Bi–N bond energy .…”

Synthesis of 4′‐Selenoribonucleosides, the Building Blocks of 4′‐SelenoRNA, Using a Hypervalent Iodine

“…The treatment of the starting material D ‐ribose with bromine in the presence of potassium carbonate gave D ‐ribonolactone ( S.1 ), which was converted to 2,3‐acetonide S.2 . In the large‐scale synthesis, when the reaction time is extended for longer than necessary, 3,5‐acetonide might be also produced (Fan, Jaenicke, & Chuah, ). However, careful monitoring of reaction progress via TLC can attenuate this drawback.…”

“…In the synthesis of 2,3-acetonide S.2 from S.1, the formation of isomeric 3,5-acetonide might be observed, as the reaction time is prolonged; the presence of this compound complicates the following reactions (Fan et al, 2011). Thus, it is advisable to quench this reaction before the formation of 3,5-acetonide is observed, even if reactant S.1 is still observable by TLC, because the desired product S.2 can be easily separated from S.1 by liquid extraction with CHCl 3 and H 2 O.…”

Synthesis of Reverse Glycosyl Fluorides and Rare Glycosyl Fluorides Enabled by Radical Decarboxylative Fluorination of Uronic Acids

“…l -Lyxose, as a rare sugar, has been identified as a component of oligosaccharide antibiotics, including flambamycin, curamycin, avilamycin, and everninomicin . There are sporatic reports describing synthesis of l -lyxose by chemical methods and biotransformations . We were pleased to find that the exposure of d -1,5-anhydrogalactinol 9 to decarboxylative fluorination to generate α- l -lyxopyranosyl fluoride 10 in 84% yields (see Scheme d).…”