Reductones

Schank, Kurt

doi:10.1055/s-1972-21845

Cited by 39 publications

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“…As shown in Figure 1(a), neutral acireductones have been proposed to adopt structures involving a six-membered ring 18. However, the X-ray structure of the rubidium salt and neutral form of triose reductone (R = R' = H) revealed that all three oxygen atoms are positioned on one side of the carbon chain (Figure 1(b)).…”

Section: Introductionmentioning

confidence: 99%

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity

2008

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Using a new N 4 -donor chelate ligand having a mixture of hydrophobic phenyl and hydrogen bond donor appendages, a trinuclear Ni(II) complex of the doubly deprotonated form of 2-hydroxy-1,3-diphenylpropane-1,3-dione was isolated, characterized (X-ray crystallography, elemental analysis, UV-vis, 1 H NMR, FTIR, magnetic moment measurement), and evaluated for O 2 reactivity. This complex, [(6-NA-6-Ph 2 TPANi) 2 (μ-PhC(O)C(O)C(O)Ph) 2 Ni](ClO 4 ) 2 (4), has two terminal pseudo octahedral Ni(II) centers supported by the tetradentate chelate ligand, and a central square planar Ni (II) ion ligated by oxygen atoms of two bridging enediolate ligands. In CH 3 CN, 4 exhibits a deep orange/brown color and λ max = 463 nm (ε = 16,000 M -1 cm -1 ). The room temperature magnetic moment of 4, determined by Evans method, is μ eff = 5.3(2) μ B . This is consistent with the presence of two non-interacting high-spin Ni(II) centers, a diamagnetic central Ni(II) ion, and an overall quintet ground state. Exposure of a CH 3

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Section: Introductionmentioning

confidence: 99%

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity

2008

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“…Wird als disubstituiertes Diazomethan 2-Diazopropan (2b') eingesetzt, dann verläuft die Umsetzung mit den vorgenannten vicinalen Trionen selbst bei À 788 noch stark exotherm; die in Lösung nachweisbaren (1 : 1)-Dioxole 7bb', 7cb' und 7hb' sind aufgrund der Gegenwart von zwei Me-Substituenten (R 1 , R 2 Me) noch instabiler als die Dioxole 7bh', 7ch' und 7hh' und lassen sich nicht mehr unzersetzt vom Lösungsmittel befreien. Da die Lösungen der Zersetzungsprodukte positive Redukton-Nachweise [14] sowohl mit methanolischer Eisen(III)-chlorid-Lösung als auch mit Tillmans Reagenz liefern, wird auf eine spontane Ringöffnung des Dioxol-Rings zu den Redukton-Derivaten 9 geschlossen. Strukturbedingt sollten dann aus 9 in Gegenwart von Feuchtigkeit spontan die Reduktone 10b,c,h entstehen (Schema 4), die über DC-Vergleich mit unabhängig hergestellten Referenzproben zwar abgesichert, aber nicht in Substanz isoliert wurden.…”

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Chemie freier, cyclischer vicinaler Tricarbonyl-Verbindungen (`1,2,3-Trione'), Teil 1, Reaktionsweise von Diazomethan und seinen Derivaten mit 5,5-Dimethylcyclohexan-1,2,3-trion (=`Oxo-dimedon') und verwandten Cyclohexan-1,2,3-trionen

Schank

Vecchia

Lick

2001

HCA

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Teil 1Reaktionsweise von Diazomethan und seinen Derivaten mit 5,5-Dimethylcyclohexan-1,2,3-trion ( Oxo-dimedon) und verwandten Cyclohexan-1,2,3-trionen Dem Gedenken an Lennart Eberson, dem Autor der wegweisenden Monographie Electron Transfer Reactions in Organic Chemistry [16b], gewidmet.Chemistry of Free Cyclic Vicinal Tricarbonyl Compounds (1,2,3-Triones). Part 1. Reaction of Diazomethane and Its Derivatives with 5,5-Dimethylcyclohexane-1,2,3-trione ( Oxo-dimedone) and Related Cyclohexane-1,2,3-trionesInteractions of diazomethane and of its derivatives as typical nucleophiles with cyclic 1,2,3-triones as efficient electrophiles lead to different results: a) formation of oxiranes (C,O insertion under loss of N 2 ), b) nucleophilic addition yielding diazoaldols, c) formation of ring-enlargement products (C,C insertion under loss of N 2 ), and d) formation of dioxoles via redox reactions (under loss of N 2 ). Our results and those of other groups allow us to recognize that the unexpected outcome of the reaction of oxodimedone and several related species is due to a closed-shell diazoaldol formation followed by an open-shell redox reaction leading to dioxoles. Helvetica Chimica Acta ± Vol. 84 (2001) 2071 Schema 2. Typische Reaktionen von Diazoalkanen mit unsolvatisierten, cyclischen Tricarbonyl-Verbindungen im Einklang mit Befunden aus der Literatur, Ergebnisse von Schank et al. [12] Helvetica Chimica Acta ± Vol. 84 (2001) 2076 Schema 4. Bildung der Reduktone 10 aus den vicinalen Trionen 1b, c, h und 2-Diazopropan (2b') über die ringgeöffneten Dioxole 9 als Zwischenstufen Schema 6. 6,6-Dimethylcycloheptan-1,4-dion (16) aus Oxodimedon (1c) durch Ringerweiterung über den Benzylester 6cf' in einer Eintopfreaktion [12a] Schema 7. Allgemeine mechanistische Formulierung der Reaktionen von Elektronen-Donatoren (Nucleophile) mit Elektronen-Akzeptoren (Elektrophile) nach Kim und Kochi [15] Schema 8. Umsetzungen von isomeren, sterisch gehinderten Benzochinonen mit Diazomethan nach Rundel und Kästner [24]

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“…Exchange of Both Substituents of 7a ± e Providing Electron-Rich Alkynes 7m ± p. Ethyl trimethylsilylethynyl ether (7m) was ozonized to yield a mixture of ethyl 2-oxo-2-(trimethylsilyl)acetate (12) and mixed ethyl trimethylsilyl oxalate (13) (Scheme 5). The yellow crude mixture of 12 (yellow) and 13 (colorless) became colorless during introduction of a three-to fourfold excess of O 3 ; subsequent distillative workup finally afforded colorless oxalate 13.…”

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“…[12]), presumably caused by dihydroxyacrylic acid (16) [13]. The yield of 15 was indirectly determined as 17 via simultaneous esterification and derivatization by means of a soln.…”

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Chemiluminescent and Non-Chemiluminescent Ozonations of Selected Electron-Rich Alkynes in Halomethanes

Schank

Beck

Frank

2000

HCA

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Alkynes of sufficiently high nucleophilicity react with electrophilic O 3 under conversion of the alkyne function to a vicinal dicarbonyl function. Contrary to earlier investigations with alkylated or arylated acetylene, products of complete CÀC cleavage were not found as primary products, and, beyond that, peroxidic reaction products were absent. Trimethylsilylated alkynes reacted with O 3 either by uptake of two or three O-atoms, but again without CÀC cleavage or formation of peroxides. Two particularly electron-rich, symmetrically substituted alkynes revealed strong chemiluminescence during ozonation at low temperature, whereas this behavior was not observed with unsymmetrically substituted alkynes. The results are summarized in terms of a mechanistic discussion.Introduction. ± Ozonations of alkynes have been described [3] [4] far less frequently than those of alkenes. Investigations of mechanistic importance have been described by Keay and Hamilton [5]. These authors found that perfluorobut-2-yne did not react appreciably with O 3 at À 708 in CH 2 Cl 2 , whereas slow conversion was observed with Phsubstituted alkynes, and fast conversions were observed with acetylene itself and with alkyl-substituted acetylenes. Successful conversions with O 3 yielded peroxidic reaction mixtures that were able to epoxidize cyclohexene. The resulting peroxidic species 1 ± 5 are depicted below.An independent paper of Jackson and Hull [6] on ozonation of diphenylacetylene published at the same time mentioned 1,2-dioxetane (6a) as a possible intermediate because of the indirect chemiluminescence [7] observed during thermal decomposition to 6b in the presence of fluorescers (Scheme 1).However, structures like 6a that do not possess a CO group were earlier ruled out on the basis of IR investigations (CO group found at 1740 cm À1 ) by De More and Lin [8] in the cases of acetylene and its mono-and dialkylated derivatives during

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Reductones

Cited by 39 publications

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A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity

Chemie freier, cyclischer vicinaler Tricarbonyl-Verbindungen (`1,2,3-Trione'), Teil 1, Reaktionsweise von Diazomethan und seinen Derivaten mit 5,5-Dimethylcyclohexan-1,2,3-trion (=`Oxo-dimedon') und verwandten Cyclohexan-1,2,3-trionen

Chemiluminescent and Non-Chemiluminescent Ozonations of Selected Electron-Rich Alkynes in Halomethanes

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Reductones

Cited by 39 publications

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A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O2 Reactivity

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O2 Reactivity

Chemie freier, cyclischer vicinaler Tricarbonyl-Verbindungen (`1,2,3-Trione'), Teil 1, Reaktionsweise von Diazomethan und seinen Derivaten mit 5,5-Dimethylcyclohexan-1,2,3-trion (=`Oxo-dimedon') und verwandten Cyclohexan-1,2,3-trionen

Chemiluminescent and Non-Chemiluminescent Ozonations of Selected Electron-Rich Alkynes in Halomethanes

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A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O₂ Reactivity