Synthesis of Nonulosonic Acids

Abstract

Bacterial cell‐surface nonulosonic acids are unique in their structural complexity and their biological roles in life processes. Their presence at the non‐reducing end of bacterial cell surface glycans makes them key players in infections related to various multidrug‐resistant pathogens. These glycans are difficult to isolate from natural sources in pure form. Also, due to their complicated structures, access to these rare sugars through synthesis is highly challenging. The most well‐studied bacterial nonulosonic acid is pseudaminic acid which has been synthesized by many groups and reviewed very recently. In this minireview, we discuss the recent advances in the synthesis of remaining nonulosonic acids viz. legionaminic acid, acinetaminic acid, and fusaminic acid.

Electrochemical Oxidation of Glycine with Bimetallic Nickel−Manganese Oxide Catalysts

“…The small peaks at 560 and 619 cm À 1 denote MnÀ O octahedral and MnÀ O tetrahedral sites, respectively, that show good agreement with the literature. [36] It is noticeable that NiMn 2 O 4 and Ni 1 . 5 Mn 1.5 O 4 do not contain NiO stretching at 364 cm À 1 and MnÀ O stretching at 560 cm À 1 .…”

Biocatalysis making waves in organic chemistry

“…Pyruvate dependent aldolases play a central role in the synthesis of ulosonic acids and sialic acids which has recently been reviewed 35,39,80,81,101,102 and a longstanding industrial example illustrates the power of the approach (Scheme 8), dating back to the first wave of biocatalysis. [103][104][105][106] Class II pyruvate dependent aldolases are part of the lignin and polycyclic aromatic compound degrading enzymes.…”

An efficient and scalable synthesis of 2,4-di-N-acetyl-l-altrose (l-2,4-Alt-diNAc)

“…Benzyl 2-O-acetyl-3,4-O-isopropylidene-a-L-fucopyranoside (10) and benzyl 2-O-acetyl-3,4-O-isopropylidene-b-L-fucopyranoside (14). To a solution of L-fucose 6 (11.0 g, 67.0 mmol) in benzyl alcohol (22 mL), was added p-toluenesulfonic acid (0.5 g), and the mixture was stirred and heated to 130 C for 30 min.…”

“…In the biosynthesis of Pse, the intermediate 2,4-dideoxy-2,4-diacetamido-L-altrose (L-Alt-diNAc, 5) is enzymatically extended via an aldol condensation with phosphoenolpyruvate (PEP). 12,13 Analogously, suitably protected L-Alt-diNAc substrates have also been used for the chemical synthesis of Pse, typically by reaction with methyl 2-(bromomethyl)acrylate via indium-mediated allylation, 14 followed by an ozonolysis to cleave the alkene, revealing the desired 3-keto functionality. There have to date been several chemical syntheses of Pse reported in literature with varying success; some suffered from long reaction sequences, others from low overall yield, or difficulty in scaling up.…”