Corrin Syntheses. Part IV

Bertele, Erhard; Scheffold, Rolf; Gschwend, Heinz W.; Pesaro, M.; Fischli, Albert; Roth, Martin; Schossig, Jürgen; Eschenmoser, Albert

doi:10.1002/hlca.201200342

Cited by 12 publications

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“…presence of cyanide; cf.P art IV [2], Chapt. A), led to complex mixtures of partially oxidized material, whereas treatment of 13a or 13c with the DMF solvate of Co(ClO 4 ) 2 in MeCN under Ar,followedbyCo II!III oxidation with air in the presence of 1n HCl/NaCl, and finally workupo fw hat presumablyc onstitutedt he dichloro-Co III -complex with KCN,a fforded crystalline 22 in up to 90% yield.…”

Section: )V Orgängig War Man Auf Die Existenz Einess Olchen (Liàcorrimentioning

confidence: 99%

“…Fig. 6imTeil IV [2]);die Identität der auf den beiden Wegen gewonnenen Proben wurde spektroskopisch sichergestellt. Die Einführung von Metall-Ionen wie Co [11],C uu nd Zn [21],s owie neulichauch von Rh [33] in natürliche metallfreie Corrinoide wurdevon Toohey [11] (vgl.…”

Section: )V Orgängig War Man Auf Die Existenz Einess Olchen (Liàcorriunclassified

“…corrin cyclization within a non-robust Zn II complex. Most prominent among our studies of the properties of the metal-free corrin ligands are the complexations with various metal ions.W ealso describe experiments on the introduction of Me groups into the meso-positions of dicyano-Co 2,2,7,7,12,, i.e., experiments carried out as model study for corresponding methylations tepsi nt he finals tage of the Harvard/ETH vitamin B 12 project.Chapter A: A ! B Ring Closure by Sulfide Contraction via Oxidative Coupling:S ynthesiso frac-Chloro-zink(II)-15-cyano-1,2,2,7, 7, 12,12-heptamethylcorrinate [3][5] [6].…”

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“…6 ! 7,the Zn II ion seems to play a triple role:f irst, it presumablyf acilitates the first two steps;s econd, it hamperst he third step,a nd supposedly has to leave the ligando f 5 in ordert oa llow the contraction proceed, and, third, it finally has to re-enter the ligand in order to stabilize it, such that 6 can be isolated and finally desulfurized under acidic conditions to give 7.Not only were all these observation important to optimize the preparative procedure for the synthesis of the Zn II complex 7 in the modelsynthesis of the metalfree corrin ligand 13 (Fig.5) B. Herstellungu nd Eigenschaften vonS alzen des rac- 2,2,7,7,12,[5] [6] [10]. -D er leicht in kristalliner Form erhältliche Chloro-Zn II -corrin-Komplex 7 erwies sich als ein zur Herstellungd es entsprechenden metallfreien Corrin-Liganden hervorragend geeignetes Zwischenprodukt.…”

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“…Um das Jahr 1968 hatten Edmond und Crawford-Hodgkin von dem hier beschriebenen rac- 2,2,7,7,12,). D ie Ergebnissed er Analyse sind in [23]d argelegt worden; Fig.6, b,g ibt hierüber einen qualitativen Überblick 20 ).…”

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Corrin Syntheses. Part V

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Preparation of Metal-Free Corrin Derivatives via A ! B Ring Closure. Complexationo fthe Corrin Chromophore withMetal Ions, and Some Properties of the Ligandsi nC orrin ComplexesIn 1965, J. I. Toohey [11],w orking in the laboratoryo fH. A. Baker at Berkeley,i solated Co-free natural corrinoids from photosynthesizingb acteria. This discovery,t ogether with the challenge to prepare and to study corrin complexes containing also metal ions other than those of transition metals, led to the quest for as ynthesis of metal-freec orrin ligands.H erein, we describe how this goal was achieved in 1968 in the heptamethyl series through adaptation of the sulfide contractionmethodology (cf.P art VI of this series)t ot he problemo fa chieving an A/B-secocorrin ! corrin cyclization within a non-robust Zn II complex. Most prominent among our studies of the properties of the metal-free corrin ligands are the complexations with various metal ions.W ealso describe experiments on the introduction of Me groups into the meso-positions of dicyano-Co 2,2,7,7,12,, i.e., experiments carried out as model study for corresponding methylations tepsi nt he finals tage of the Harvard/ETH vitamin B 12 project.Chapter A: A ! B Ring Closure by Sulfide Contraction via Oxidative Coupling:S ynthesiso frac-Chloro-zink(II)-15-cyano-1,2,2,7, 7, 12,12-heptamethylcorrinate [3][5] [6]. Thec hapter describes the adaptation of the sulfide contraction C,C-condensation method (cf.P art VI of this series)t ot he A/B-secocorrin ! corrin-cyclizationstep in the synthesiso faZ n II -corrin complex. Corrin complexes of non-transition metals such as Zn are non-robust in the sense that the metal ion can be removed without destruction of the corrin ligand. Thes earch for optimal reaction conditions of the C,C-bondforming sulfide-contraction step required extensivee xperimentation and led to observations that turned out to be essential for the application of the A ! B macroring-closure method in the synthesis of vitamin B 12 . Chapter B: Preparationand Properties of Salts of rac-15-Cyano-1,2,2,7,7,12,12-heptamethylcorrinium Cations [3][5][6]. Azidolytic decomplexation of aZ n II -heptamethyl-corrin complex led to the first Helv eticaChimica Acta -V ol. 98 (2015)1845 2015 Verlag Helvetica Chimica Acta AG,Z ürich 1 ) Teile I und IV vgl. [1] und [2]. Der Teil V umfasst Ergebnisse aus den Promotionsarbeiten von A. Fischli [3] (1964 -1967), vgl. Fussnote 1i n[ 2], E.-L. Winnacker [4] (1964 -1968) und H.-U.B laser [5] (1967 -1970), sowie aus Postdoktoratsarbeiten von D. Bormann (1966, J. Schossig ( ) und N. Hashimoto (1970). Ein Te il der hier beschriebenenE rgebnisse war Gegenstand vorläufiger Mitteilungen[ 6-8] und Vorträge[ 9] [10].synthesis of ac orrin as metal-free N-protonated corrinium salt. Metal ions were introducedi nto the corrinium ligand to form aw ide variety of robust and non-robust corrin complexes.I mportantly,t he neutral form of the synthetic corrin ligand prefers to exist in as ensitive tautomeric form, featuring a second NH group and an olefinic bond in an e...

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Section: )V Orgängig War Man Auf Die Existenz Einess Olchen (Liàcorrimentioning

confidence: 99%

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Corrin Syntheses. Part V

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Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid

et al. 2020

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The (formal) replacement of Co in cobalamin (Cbl) by Ni II generates nibalamin (Nibl), an ew transition-metal analogue of vitamin B 12 .Described here is Nibl,synthesized by incorporation of aN i II ion into the metal-free B 12 ligand hydrogenobalamin (Hbl), itself prepared from hydrogenobyric acid (Hby). The related Ni II corrin nibyricacid (Niby)was similarly synthesized from Hby,t he metal-free cobyric acid ligand. The solution structures of Hbl,a nd Niby and Nibl, were characterized by spectroscopic studies. Hbl features two inner protons bound at N2 and N4 of the corrin ligand, as discovered in Hby.X-rayanalysis of Niby shows the structural adaptation of the corrin ligand to Ni II ions and the coordination behavior of Ni II .T he diamagnetic Niby and Nibl,a nd corresponding isoelectronic Co I corrins,w ere deduced to be isostructural. Nibl is as tructural mimic of four-coordinate base-off Cbls,a sv erified by its ability to act as as trong inhibitor of bacterial adenosyltransferase.

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Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid

et al. 2020

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Corrin Syntheses. Part IV

Cited by 12 publications

References 55 publications

Corrin Syntheses. Part V

Corrin Syntheses. Part V

Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid

Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid

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Corrin Syntheses. Part IV

Cited by 12 publications

References 55 publications

Corrin Syntheses. Part V

Corrin Syntheses. Part V

Replacement of the Cobalt Center of Vitamin B12 by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B12 Ligands Hydrogenobalamin and Hydrogenobyric Acid

Replacement of the Cobalt Center of Vitamin B12 by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B12 Ligands Hydrogenobalamin and Hydrogenobyric Acid

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Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid

Replacement of the Cobalt Center of Vitamin B₁₂ by Nickel: Nibalamin and Nibyric Acid Prepared from Metal‐Free B₁₂ Ligands Hydrogenobalamin and Hydrogenobyric Acid