Tautomer Structures in Ketose–Aldose Transformation of 1,3-Dihydroxyacetone Studied by Infrared Electroabsorption Spectroscopy

Chen, Serena H.; Hiramatsu, Hirotsugu

doi:10.1021/acs.jpcb.9b08557

Cited by 7 publications

(8 citation statements)

References 55 publications

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“…These experiments led to the observation that, at equilibrium, the mixture was composed of 60–65% DHA and 35–40% glyceraldehyde regardless of the starting point (pure DHA or pure Gld) [ 82 ]. This observation confirmed that DHA is more thermodynamically stable than Gld at room temperature ( Figure 8 ) [ 82 , 84 , 85 ].…”

Section: A Multi-functional Synthesis Tool: Dha’s Broad Range Of Reac...supporting

confidence: 72%

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

et al. 2023

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1,3-dihydroxyacetone (DHA) is an underrated bio-based synthon, with a broad range of reactivities. It is produced for the revalorization of glycerol, a major side-product of the growing biodiesel industry. The overwhelming majority of DHA produced worldwide is intended for application as a self-tanning agent in cosmetic formulations. This review provides an overview of the discovery, physical and chemical properties of DHA, and of its industrial production routes from glycerol. Microbial fermentation is the only industrial-scaled route but advances in electrooxidation and aerobic oxidation are also reported. This review focuses on the plurality of reactivities of DHA to help chemists interested in bio-based building blocks see the potential of DHA for this application. The handling of DHA is delicate as it can undergo dimerization as well as isomerization reactions in aqueous solutions at room temperature. DHA can also be involved in further side-reactions, yielding original side-products, as well as compounds of interest. If this peculiar reactivity was harnessed, DHA could help address current sustainability challenges encountered in the synthesis of speciality polymers, ranging from biocompatible polymers to innovative polymers with cutting-edge properties and improved biodegradability.

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Section: A Multi-functional Synthesis Tool: Dha’s Broad Range Of Reac...supporting

confidence: 72%

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

et al. 2023

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“…For DHA reduction, we hold first potential at 0 V versus RHE to collect the reference spectrum. When we applied negative potentials from 0 V to −1.1 V versus RHE, a positive band at 1736 cm –1 was observed, which could be assigned to CO stretching of the carbonyl group in DHA, indicating the consumption of DHA in the thin layer between the electrode and the prism. The peaks at 1431 and 1257 cm –1 are ascribed to CH 3 and CH 2 deformations and C–C–H deformation, respectively. , These features can be attributed to either the reactant DHA or the acetol, that is the first reduction product (see transmission spectra of DHA and acetol in Figure S9).…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reduction of the Simplest Monosaccharides: Dihydroxyacetone and Glyceraldehyde

et al. 2020

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Dihydroxyacetone (DHA) and glyceraldehyde (GA)the simplest monosaccharides in natureare both essential building blocks in organic synthesis. There have been detailed investigations on the selective production of DHA and GA through the platinum-catalyzed electrochemical oxidation of glycerol, which is a surplus byproduct from biodiesel. However, less attention has been paid to the electrochemical behavior of DHA and GA themselves. Here, we report the electrochemical reduction of DHA and GA at different pH on platinum and palladium electrodes. Palladium exhibits a superior activity toward both the dehydroxylation and hydrogenation of DHA and GA. Using online high-performance liquid chromatography, we show that both DHA and GA display a two-step reduction. In particular, DHA is reduced first to acetol and then sequentially to acetone, while GA is first reduced to 3-hydroxypropionaldehyde (3-HPA), followed by hydrogenation to 1,3-propanediol. The reduction of both molecules is accompanied by a poisoning of the catalyst surface. In situ Fourier-transform infrared spectroscopy measurements suggest adsorbed carbon monoxide as the poisoning species, resulting from the dissociative adsorption of DHA and GA. Mechanistic reaction pathways for both DHA and GA reduction are proposed and discussed.

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“…To investigate this possibility, we focused on controlling the fate of hemiaminal 21, the intermediate from which 5-OP-RU (kinetic product) or the lumazine (thermodynamic product via 23 and 24) would competitively form. We hypothesized that, as imine formation in polar solvents typically proceeds via the iminium intermediate (22), aprotic polar solvents might stabilize the cation while avoiding solvent attack on iminium 22, thus diverting the reaction toward 5-OP-RU.…”

Section: Synthesis Of 5-op-rumentioning

confidence: 99%

“… a Tautomerization and in situ dehydration of 1,3-dihydroxyacetone ( 14 ) to trace methylglyoxal ( 11 ) at 80 °C could produce 5-OP-RU ( 3 ) during the synthesis of rRL-6-HM ( 15 ). …”

Section: Discovery Of Antigens For Mait Cellsmentioning

confidence: 99%

Chemical Modulators of Mucosal Associated Invariant T Cells

2021

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Conspectus Over the past decade, we have contributed to the chemistry of microbial natural products and synthetic ligands, related to riboflavin and uracils, that modulate immune cells called mucosal associated invariant T cells (MAIT cells). These highly abundant T lymphocytes were only discovered in 2003 and have become recognized for their importance in mammalian immunology. Unlike other T cells, MAIT cells are not activated by peptide or lipid antigens. In collaboration with immunology and structural biology research groups, we discovered that they are instead activated by unstable nitrogen-containing heterocycles synthesized by bacteria. The most potent naturally occurring activating compound (antigen) is 5-(2-oxopropylideneamino)-d-ribitylaminouracil (5-OP-RU). This compound is an imine (Schiff base) formed through condensation between an intermediate in the biosynthesis of riboflavin (vitamin B2) and a metabolic byproduct of mammalian and microbial glycolysis. Although it is very unstable in water due to intramolecular ring closure or hydrolysis, we were able to develop a non-enzymatic synthesis that yields a pure kinetically stable compound in a nonaqueous solvent. This compound has revolutionized the study of MAIT cell immunology due to its potent activation (EC50 = 2 pM) of MAIT cells and its development into immunological reagents for detecting and characterizing MAIT cells in tissues. MAIT cells are now linked to key physiological processes and disease, including antibacterial defense, tissue repair, regulation of graft-vs-host disease, gastritis, inflammatory bowel diseases, and cancer. 5-OP-RU activates MAIT cells and, like a vaccine, has been shown to protect mice from bacterial infections and cancers. Mechanistic studies on the binding of 5-OP-RU to its dual protein targets, the major histocompatibility complex class I related protein (MR1) and the MAIT cell receptor (MAIT TCR), have involved synthetic chemistry, 2D 1H NMR spectroscopy, mass spectrometry, computer modeling and molecular dynamics simulations, biochemical, cellular, and immunological assays, and protein structural biology. These combined studies have revealed structural influences for 5-OP-RU in solution on protein binding and antigen presentation and potency; informed the development of potent (EC50 = 2 nM) and water stable analogues; led to fluorescent analogues for detecting and tracking binding proteins in and on cells; and enabled discovery of drugs and drug-like molecules that bind MR1 and modulate MAIT cell function. MAIT cells offer new opportunities for chemical synthesis to enhance the stability, potency, selectivity, and bioavailability of small molecule ligands for MR1 or MAIT TCR proteins, and to contribute to the understanding of T cell immunity and the development of prospective new immunomodulating medicines.

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Tautomer Structures in Ketose–Aldose Transformation of 1,3-Dihydroxyacetone Studied by Infrared Electroabsorption Spectroscopy

Cited by 7 publications

References 55 publications

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

Electrochemical Reduction of the Simplest Monosaccharides: Dihydroxyacetone and Glyceraldehyde

Chemical Modulators of Mucosal Associated Invariant T Cells

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