New Chemical and Biochemical Developments in the Vitamin B<sub>12</sub> Field

Bernhauer, Konrad; Müller, Otto; Wagner, Fritz

doi:10.1002/anie.196402001

Cited by 37 publications

(17 citation statements)

References 66 publications

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“…Melting points were determined on a SGW X-4 micro melting point instrument. 1 H and 13 C NMR spectra were recorded on Bruker 400 or 500 MHz spectrometer. IR spectra were obtained on a PerkinElmer FT-IR system.…”

Section: Methodsmentioning

confidence: 99%

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

Liu

Nie

Yao

et al. 2014

Journal of Chemical Research

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Section: Methodsmentioning

confidence: 99%

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

Liu

Nie

Yao

et al. 2014

Journal of Chemical Research

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“…Hydrogen is formed by the reaction of the hydride with a proton. 395 With the presence of vitamin B 12 -type compounds, other reactions such as reduction of alkyl halides, 396 reductive dechlorinations 397,399 and intramolecular rearrangements, 389 have also been reported.…”

Section: Scheme 10mentioning

confidence: 99%

Three characteristic reactions of organocobalt compounds in organic synthesis

Omae

2007

Applied Organom Chemis

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Organocobalt compounds in organic synthesis have three characteristic reactions. The first occurs because cobalt has a high affinity to carbon-carbon π -bonds or carbon-nitrogen π -bonds. The second occurs because cobalt has a high affinity to carbonyl groups. The third is due to cobalt easily tending to form square-planar bipyramidal six-coordination structures with four nitrogen atoms or two nitrogen atoms and two oxygen atoms at the square-planar position, and to bond with one or two carbon atoms at the axial position. The first characteristic reactions are the representative reactions of organocobalt compounds with a mutually bridged bond between the two π -bonds of acetylene and the cobalt-cobalt bond of hexacarbonyldicobalt. These are reactions with a Co 2 (CO) 6 INTRODUCTIONOrganometallic intramolecular coordination compounds, especially five-membered ring compounds of organotin compounds, have been studied since 1965, and many reviews 1 -13 and some books 14 -16 have published on the subject. These compounds are mainly synthesized by cyclometalation reactions with transition metal compounds. The first publication on this subject is generally considered to be the reaction of diazobenzene with nick elocene by Kleiman and Dubeck 17 in 1963 as shown in equation (1).*Correspondence to: Iwao Omae, Nihon Pharmaceutical University, 10281, Komuro, Ina-cho, Saitama, An earlier article on the direct synthesis of 2-phenyl-3-indazolinone by carbonylation of azobenzene with a cobalt Materials, Nanoscience and CatalysisThree characteristic reactions of organocobalt compounds 319 carbonyl catalyst, as shown in equation (2), was published in 1956. 18 It was also synthesized in 1967 through a twostep reaction, that is, (i) cyclopalladation of azobenzene via the five-membered ring product, and (ii) carbonylation, as shown in equation (3). 19From these two reactions, the former reaction [equation (2)] is presumed also to proceed via cyclometallation, that is, cyclocobaltation with the cobalt carbonyl catalyst, as shown in equation (4). Actually, many cyclomatalations with cobalt compounds have been reported. 20 -35 For example, a similar cyclometalated organocobalt compound was prepared by the reaction of azobenzene with methyltetra(trimethylphosphine)cobalt, as shown in equation (5). 20 Further, one year previously, in 1955, the same type of heterocyclic compound was prepared by the same type of carbonylation reaction with an organocobalt compound, as shown in equation (6). 36 This publication by Murahashi 36 may be considered to be the first reaction relating cyclometalation reactions.In the chemical industry, organocobalt is an essential constituent in many important catalysts. Specifically, they are key components in the multimillion-pound technology of hydroformylation; that is, the catalytic transformation of olefins into aldehydes using homogeneous catalysts. This article reports on three characteristic reactions of the organocobalt compounds in organic syntheses on the basis of their structures and reactivities...

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“…19–22 The alkyl radical and Co(II) photoproducts ( 2 ) are identical to the intermediates formed in the enzyme-catalyzed reactions and thus offers a relatively simple means to model B 12 -dependent transformations. In addition, the C–Co bond is weak (<30 kcal/mol), and the energies supplied by any of the wavelengths absorbed by the corrin ring system (330–560 nm) are sufficient to induce cleavage with high quantum yields.…”

Section: Introductionmentioning

confidence: 99%

Vitamin B₁₂: A Tunable, Long Wavelength, Light-Responsive Platform for Launching Therapeutic Agents

2015

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CONSPECTUS Light-responsive agents offer the promise of targeted therapy, whose benefits include (i) prolonged action at the target site, (ii) overall reduced systemic dosage, (iii) reduced adverse effects, and (iv) localized delivery of multiple agents. Although photoactivated prodrugs have been reported, these species generally require short wavelengths (<450 nm) for activation. However, maximal tissue penetrance by light occurs within the “optical window of tissue” (600–900 nm), well beyond the wavelength range of most existing photocleavable functional groups. Furthermore, since multidrug therapy holds promise for the treatment of complex diseases, from cancer to neurological disorders, controlling the action of multiple drugs via wavelength modulation would take advantage of a property that is unique to light. However, discrimination between existing photoresponsive moieties has thus far proven to be limited. We have developed a vitamin B12/light-facilitated strategy for controlling drug action using red, far-red, and NIR light. The technology is based on a light-triggered reaction displayed by a subset of B12 derivatives: alkyl-cob(III)alamins suffer photohomolysis of the C–Co(III) bond. The C–Co(III) bond is weak (<30 kcal/mol), and therefore all wavelengths absorbed by the corrin ring (330–580 nm) induce photocleavage. In addition, by appending fluorophores to the corrin ring, long wavelength light (>600 nm) is readily captured and used to separate the Co-appended ligand (e.g., a drug) from B12. Consequently, it is now feasible to preassign the wavelength of homolysis by simply installing a fluorescent antenna with the desired photophysical properties. The wavelength malleability inherent within this strategy has been used to construct photoresponsive compounds that launch different drugs by simply modulating the wavelength of illumination. In addition, these phototherapeutics have been installed on the surface and interior of cells, such as erythrocytes or neural stem cells, and released upon expoure to the appropriate wavelength. We have shown that cytotoxic agents, such as doxorubicin, anti-inflammatories, such as dexamethasone, and anti- and pro-vascular agents are readily released from cellular vehicles as biologically active agents. We have also demonstrated that the concept of “optical window of tissue” phototherapeutics is not just limited to prodrugs. For example, stem cells have received considerable attention in the area of regenerative medicine. Hydrogels serve as scaffolds for stem cell growth and differentiation. We have shown that the formation of hydrogels can be triggered, in the presence of cells, using appropriately designed alkyl-cob(III)alamins and long wavelength light. The potential applications of phototherapeutics are broad and include drug delivery for a variety of indications, tissue engineering, and surgery.

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New Chemical and Biochemical Developments in the Vitamin B₁₂ Field

Cited by 37 publications

References 66 publications

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

Three characteristic reactions of organocobalt compounds in organic synthesis

Vitamin B₁₂: A Tunable, Long Wavelength, Light-Responsive Platform for Launching Therapeutic Agents

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New Chemical and Biochemical Developments in the Vitamin B12 Field

Cited by 37 publications

References 66 publications

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

One-Pot Synthesis of 2-Alkyl-4(5)-Aryl-1H-Imidazoles from 1-Aryl-2-Bromoethanones, Ammonium Carbonate and Aliphatic Carboxylic Acids

Three characteristic reactions of organocobalt compounds in organic synthesis

Vitamin B12: A Tunable, Long Wavelength, Light-Responsive Platform for Launching Therapeutic Agents

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Product

Resources

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New Chemical and Biochemical Developments in the Vitamin B₁₂ Field

Vitamin B₁₂: A Tunable, Long Wavelength, Light-Responsive Platform for Launching Therapeutic Agents