Metal glycosylidenes: novel organometallic tools for C-glycosidation

Dötz, Karl Heinz; Jäkel, Christoph; Haase, Wilm‐Christian

doi:10.1016/s0022-328x(00)00650-1

Cited by 60 publications

(16 citation statements)

References 75 publications

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“…Little by little, research into carbon-metal bonds in natural systems became established [23,122]. Historical primacy belongs to vitamin B 12 , its coenzyme and methylcobalamin [16,123,124] which were long considered the only naturallyoccurring compounds with a metal-carbon bond. The story begins with the observation that raw liver is a cure for an otherwise fatal condition, pernicious anemia.…”

Section: Naturally-occurring Organometallics and Synthetic Modelsmentioning

confidence: 99%

“…For these reasons, the organometallic chemistry of the P-450 cytochromes, widely covered elsewhere, will not be revisited here. This chemistry was started by two groups, that of D. Mansuy on the porphyrin 1280vch01.pmd 28.09.2005, 17:54 24 iron carbene complexes [12] and that of R. Guilard on σ-alkyl type complexes [184]. For leading references see [185][186][187][188][189][190][191].…”

Section: Naturally-occurring Organometallics and Synthetic Modelsmentioning

confidence: 99%

“…Subsequently, metal carbene complexes of carbohydrates were synthesized [238][239][240][241][242]. In a series of papers, Dötz and coworkers [12,243] introduced the "Fischer-type carbene functionality" into carbohydrates by using a number of different synthetic methodologies; these complexes can be used for the modification of sugars. Cyclopentadienyl-titanium complexes with chiral σ-coordinated ligands derived from glucose are stereoselective reagents in organic synthesis [244,245].…”

Section: Organometallic Chemistry and Aqueous Solventsmentioning

confidence: 99%

“…CO, alkyls, π-bonded species) or biomolecules (steroids, amino acids, sugars, peptides, DNA, vitamins, enzymes, antibodies) attached by direct metalcarbon linkages, but all having in common their ability to play a role in biological processes. This by no means exhaustive list should give an idea of the potential scope of this field [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

mentioning

confidence: 99%

“…This opening chapter aims to address this period of induction and emergence, viewed from today's perspective, and to attempt to show the development of the founding principles of this field, which is multidisciplinary by definition and thus requires advances on several fronts for its own development. In this respect, it is remarkable that one of the factors leading to the explosion of the field was the enhanced understanding of the metal-carbon (M-C) bond, with the result that all studies up to and including the structure of vitamin B 12 consider only σ bonds [16][17][18]. However, following the discovery of ferrocene and its sandwich structure [19][20][21], we see the establishment of a theoretical basis for the understanding of new types of M-C bonds (σ, π and δ) such as, for example, those of metallocenes, metal carbonyls or metal carbenes (Scheme 1.1).…”

mentioning

confidence: 99%

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A Novel Field of Research: Bioorganometallic Chemistry, Origins, and Founding Principles

2005

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Section: Naturally-occurring Organometallics and Synthetic Modelsmentioning

confidence: 99%

Section: Naturally-occurring Organometallics and Synthetic Modelsmentioning

confidence: 99%

Section: Organometallic Chemistry and Aqueous Solventsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A Novel Field of Research: Bioorganometallic Chemistry, Origins, and Founding Principles

2005

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The Synthesis of Phenols and Quinones viaFischer Carbene Complexes

Waters

Wulff

2008

Organic Reactions

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Fischer carbene complexes can be broadly defined as those transition‐metal carbene complexes that have a low oxidation state, have an electrophilic carbene carbon , and usually have a heteroatom‐stabilizing substituent on the carbene carbon. Fischer complexes were the first examples of any type of transition metal carbene complexes to be reported. The reaction of Fischer carbene complexes with alkynes is facile, occurring just above ambient temperature, and resulting in the assembly of a benzene ring from the three carbons of the alpha, beta‐unsaturated carbine complex, the two carbons of the alkyne, and the carbon of a carbon monoxide ligand. The synthetic value of this reaction stems from its broad scope, the generally high yields for the process, and the fact that that the products can function as intermediates for the synthesis of a variety of aromatic compounds including para ‐quinones. It is the most synthetically valuable of the large number of Fischer carbene complexes that have been developed for applications in synthetic organic chemistry. This chapter is the first comprehensive review that is limited to the synthesis of phenols and quinones from the reactions of Fischer carbene complexes with alkynes.

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Biometallorganische Chemie: Ein faszinierendes Forschungsgebiet

Beck¹,

Severin²

2002

Chemie in unserer Zeit

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Lange Zeit galten Vitamin B 12 , das Coenzym B 12 sowie Methylcobalamin (Abbildung 3) als einzige natürlich vorkommende Verbindungen mit einer Metall-Kohlenstoff-σ-Bindung [1,10]. Das Coenzym B 12 entsteht durch Reduktion des Cobalt(III)-Corrin-Komplexes über Co II zu dem sehr elektronenreichen Co I -Komplex, an den unter Bildung der Cobalt-Kohlenstoff-σ-Bindung der Adenosylrest von ATP oxidativ addiert wird. Die Rolle des Coenzyms B 12 ist heute sehr gut erforscht. Es katalysiert die ungewöhnliche 1,2-Umlagerung (Abbildung 4), bei der ein Substituent R (z.B. eine Aminogruppe NH 2 ) durch ein H-Atom des benachbarten C-Atoms ausgetauscht wird. Viele Untersuchungen führten zu dem Schluss, dass diese Reaktion über Radikale verläuft. Durch homolytische Spaltung der Co-C-Bindung entsteht ein Adenosyl-Radikal, das ein Wasserstoffatom am C 1 -Kohlenstoff abstrahieren kann. Nach 1,2-Wanderung des Restes R an das benachbarte C-Atom erhält das nun gebildete C 2 Radikal wieder ein H-Atom vom Methyladenosyl, wobei das CH 2 -Adenosyl Radikal regeneriert wird. Das Cobalt-Radikal hat hier quasi "stand by"-Funktion. Eine wichtige weitere metallorganische Verbindung in der Natur ist Methylcobalamin, das aus Cobaltcorrin und einer Methylquelle (Methyltetrahydrofolsäure) entsteht. Methylcobalamin vermag das Methylcarbanion CH 3 − zu übertragen -z.B. entsteht aus Homocystein Methionin -und ist auch verantwortlich für die Biomethylierung von Metallionen, vor allem von Quecksilber(II) (Abbildung 5). Dabei bildet sich das stabile, wasserlösliche Methylquecksilberkation [H 3 C-Hg] + , das die Blut-Gehirn-Schranke überwinden kann und zu schweren Nervenschädigungen führt. Durch Biomethylierung von Sn (aus zinnhaltigen Antifouling-Anstrichen der Schiffe gegen Algen) oder von Arsen (aus dem früher als Malerfarbe verwendeten Schweinfurter Grün = Cuarsenit) entstehen das giftige Me 3 Sn + -Kation bzw. As(CH 3 ) 3 . Es ist sehr bemerkenswert, dass Bakterien im Laufe der Evolution einen Entgiftungsmechanismus für Alkylquecksilber-Kationen entwickelt haben [1,11]. Die Organoquecksilberlyasen (Cystein-haltige Peptide) vermögen die Alkylquecksilber-Kohlenstoff-Bindung zu spalten.Heute weiß man, dass die Cobalt-Kohlenstoff-Bindung eine ganz "normale" Bindung ist (z.B. wie eine Metall-Chlor-Bindung), mit einer Bindungsenthalpie von etwa 100 kJ/mol

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Metal glycosylidenes: novel organometallic tools for C-glycosidation

Cited by 60 publications

References 75 publications

A Novel Field of Research: Bioorganometallic Chemistry, Origins, and Founding Principles

A Novel Field of Research: Bioorganometallic Chemistry, Origins, and Founding Principles

The Synthesis of Phenols and Quinones viaFischer Carbene Complexes

Biometallorganische Chemie: Ein faszinierendes Forschungsgebiet

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