Oxygen-, nitrogen-, and sulfur-substituted heteroallenes

Reichen, Werner

doi:10.1021/cr60315a003

Cited by 56 publications

(19 citation statements)

References 53 publications

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“…The authors considered the possibility of ketene intermediates in these reactions,5a and it is now generally accepted that highly reactive ketenes are formed, but are too short‐lived for direct observation 1d. 5c,d Subsequently, the generation of nitrogen‐substituted ketenes has been extensively examined, especially with regard to their use in β‐lactam cyclization 5b–d…”

Section: Methodsmentioning

confidence: 99%

New Colorimetric Detection of Glucose by Means of Electron-Accepting Indicators: Ligand Substitution of [Fe(acac)3−n(phen)n]n+ Complexes Triggered by Electron Transfer from Glucose Oxidase

et al. 2002

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Section: Methodsmentioning

confidence: 99%

New Colorimetric Detection of Glucose by Means of Electron-Accepting Indicators: Ligand Substitution of [Fe(acac)3−n(phen)n]n+ Complexes Triggered by Electron Transfer from Glucose Oxidase

et al. 2002

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“…Due to the known propensity of N ‐isocyanates to undergo a competing dimerization at temperatures as low as −40 °C, minimizing this side reaction was considered to be crucial to achieve a milder, and a more broadly applicable aminocarbonylation reaction. Although N ‐isocyanate dimers can undergo cycloreversion and regenerate the reactive intermediate, this typically only occurs upon heating . With this in mind, the desired precursor would either need to be unlikely to undergo N ‐isocyanate dimerization; or readily undergo cycloreversion.…”

Section: Resultsmentioning

confidence: 99%

Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino‐Isocyanates

Ivanovich

Clavette

Vincent-Rocan

et al. 2016

Chemistry A European J

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The ubiquity of nitrogen heterocycles in biologically active molecules challenges synthetic chemists to develop a variety of tools for their construction. While developing metal-free hydroamination reactions of hydrazine derivatives, it was discovered that carbazates and semicarbazides can also lead to alkene aminocarbonylation products if nitrogen-substituted isocyanates (N-isocyanates) are formed in situ as reactive intermediates. At first this reaction required high temperatures (150-200 °C), and issues included competing hydroamination and N-isocyanate dimerization pathways. Herein, improved conditions for concerted intramolecular alkene aminocarbonylation with N-isocyanates are reported. The use of βN-benzyl carbazate precursors allows the effective minimization of N-isocyanate dimerization. Diminished dimerization leads to higher yields of alkene aminocarbonylation products, to reactivity at lower temperatures, and to an improved scope for a reaction sequence involving alkene aminocarbonylation followed by 1,2-migration of the benzyl group. Furthermore, fine-tuning of the blocking (masking) group on the N-isocyanate precursor, and reaction conditions relying on base catalysis for N-isocyanate formation from simpler precursors resulted in room temperature reactivity, consequently minimizing the competing hydroamination pathway. Collectively, this work highlights that controlled reactivity of aminoisocyanates is possible, and provides a broadly applicable alkene aminocarbonylation approach to heterocycles possessing the β-aminocarbonyl motif.

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“…Die Bildung der Keten‐Intermediate wurde seinerzeit nur postuliert,5a gilt aber heute als gesichert, auch wenn sie zu kurzlebig sind, um direkt beobachtet zu werden 1d. 5c,d In der Folge wurde die Bildung von stickstoffsubstituierten Ketenen, und insbesondere ihre Verwendung in der β‐Lactam‐Cyclisierung, umfassend erforscht 5b–d…”

Section: Methodsunclassified

Day‐length effects on protein localisation affect water absorption in barley (Hordeum vulgare) grains

et al. 2012

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An effect of environment (daylength) on the localisation of C hordein was demonstrated. This difference in hordein localisation was also associated with differences in malting quality with water uptake in the steeping phase being associated positively with the deeper location of C hordein. These results indicate that environmental effects on protein location may affect malting performance of barley grains.

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Oxygen-, nitrogen-, and sulfur-substituted heteroallenes

Cited by 56 publications

References 53 publications

New Colorimetric Detection of Glucose by Means of Electron-Accepting Indicators: Ligand Substitution of [Fe(acac)3−n(phen)n]n+ Complexes Triggered by Electron Transfer from Glucose Oxidase

New Colorimetric Detection of Glucose by Means of Electron-Accepting Indicators: Ligand Substitution of [Fe(acac)3−n(phen)n]n+ Complexes Triggered by Electron Transfer from Glucose Oxidase

Intramolecular Alkene Aminocarbonylation Using Concerted Cycloadditions of Amino‐Isocyanates

Day‐length effects on protein localisation affect water absorption in barley (Hordeum vulgare) grains

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