The Preparation of Riboflavin.<sup>1</sup> III. The Synthesis of Alloxazines and Isoalloxazines

Tishler, Max; Wellman, J. W.; Ladenburg, Kurt

doi:10.1021/ja01228a031

Cited by 21 publications

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“…Even under mild conditions, using dry dimethylformamide/K2C03, a solution of VIII turned black within a few minutes and no starting material could be recovered. The total synthesis reported here is a variation of the well known Tishler synthesis [31]. Although compound IX was obtained only in a very poor yield, the described synthesis was the only successful one of three different approaches that have been investigated.…”

Section: Synthesesmentioning

confidence: 99%

Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Blankenhorn

1976

European Journal of Biochemistry

121

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1. Biological nicotinamide-dependent oxidoreduction consists of reversible 2e-oxidoreduction of substrates. A mechanism involving subsequent le-steps is shown to be very unfavourable due to the high energy of the nicotinamide radical.2. Free energy relationships provide a convenient tool, allowing one to differentiate between hydride transfer and hydrogen atom transfer. It is concluded that biological nicotinamide-dependent, as well as flavin-nicotinamide oxidoreduction, proceed via hydride transfer but not via hydrogen atom transfer.3. In flavin-nicotinamide oxidoreduction, flavin-nicotinamide charge transfer complexes are very likely the catalytic intermediates, preceding transfer of hydride ion. The energy of the long-wavelength charge transfer transition of zwitterionic oxidized-nicotinamide/reduced-flavin complexes is strongly dependent on polarity. It is maximal in a highly polar environment.4. 5-Deazaflavins show the high thermodynamic radical instability of nicotinamides. They have to be considered as nicotinamide analog 2e-oxidoreductants rather than flavin analogs, therefore, lacking the ability to catalyze reversible l e -oxidoreduction, essential for many flavoenzymes.

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Section: Synthesesmentioning

confidence: 99%

Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Blankenhorn

1976

European Journal of Biochemistry

121

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“…As previously mentioned, the reductive amination conditions developed for the synthesis of 1 were effective en route to 2 . However, established strategies employed aniline 4 , which can be converted to the ribitylated intermediate 10 via further aromatic functionalization (Figure ) . To avoid this late-stage functionalization, the commercially available diamine 8 was utilized.…”

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confidence: 99%

Improved Chemical Syntheses of 1- and 5-Deazariboflavin

Carlson

Kiessling

2004

J. Org. Chem.

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The cofactor flavin adenine dinucleotide (FAD) is required for the catalytic activity of a large class of enzymes known as flavoenzymes. Because flavin cofactors participate in catalysis via a number of different mechanisms, isoalloxazine analogues are valuable for mechanistic studies. We report improved chemical syntheses for the preparation of the two key analogues, 5-deazariboflavin and 1-deazariboflavin.

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“…Riboflavin for use in both human and animal nutrition has been industrially manufactured since 1950s by chemical synthesis from ribose (which is easily obtained from glucose), 3,4-dimethylaniline, and barbituric acid [ 282 , 324 , 325 ]. Fermentation processes employing some microbial strains that produce riboflavin in amounts exceeding their own metabolic requirements were implemented at industrial scale in the 1990s [ 282 , 295 ].…”

Section: Riboflavin—vitamin Bmentioning

confidence: 99%

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

et al. 2022

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This review summarizes the current knowledge on essential vitamins B1, B2, B3, and B5. These B-complex vitamins must be taken from diet, with the exception of vitamin B3, that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B3, is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

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The Preparation of Riboflavin.¹ III. The Synthesis of Alloxazines and Isoalloxazines

Cited by 21 publications

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Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Improved Chemical Syntheses of 1- and 5-Deazariboflavin

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

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The Preparation of Riboflavin.1 III. The Synthesis of Alloxazines and Isoalloxazines

Cited by 21 publications

References 0 publications

Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Nicotinamide‐Dependent One‐Electron and Two‐Electron (Flavin) Oxidoreduction : Thermodynamics, Kinetics, and Mechanism

Improved Chemical Syntheses of 1- and 5-Deazariboflavin

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

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The Preparation of Riboflavin.¹ III. The Synthesis of Alloxazines and Isoalloxazines