Sulfonium ylides derived from 2-hydroxy-benzoquinones: crystal and molecular structure and their one-step conversion into Mannich bases by amine N-oxides

Rosenau, Thomas; Mereiter, Kurt; Jäger, Christian; Schmid, Peter; Kosma, Paul

doi:10.1016/j.tet.2004.05.015

Cited by 12 publications

(6 citation statements)

References 7 publications

(4 reference statements)

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“…Special attention was paid to the question of whether the three key chromophores would again be present altogether in most-or even all-samples. The three key chromophores can be determined specifically, either by their spectroscopic features (Hosoya et al 2013a(Hosoya et al , b, 2014 or by precipitation as sulfonium ylides (Rosenau et al 2004c). The sum content of the three key chromophores in relation to the overall amount of isolated chromophores was determined as weight percentage.…”

Section: Resultsmentioning

confidence: 99%

Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in cellulosics, XII

et al. 2015

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The chromophore release and identification method isolates well-defined chromophoric substances from different cellulosic matrices, such as highly bleached pulps, cotton linters, bacterial cellulose, viscose or lyocell fibers, and cellulose acetates. The chromophores are present only in extremely low (ppm to ppb) concentrations. The concept of primary and secondary chromophores is introduced, with primary chromophores arising only from the polysaccharides inherent to cellulosic materials. Secondary chromophores also include atoms from the chemicals used to process the cellulose. Most primary chromophores belong to one of three compound classes: hydroxy-[1,4]-benzoquinones, hydroxy-[1,4]-naphthoquinones, and hydroxyacetophenones. Among them, three individual compounds dominate: 2,5-dihydroxy-[1,4]-benzoquinone, 5,8-hydroxy-[1,4]-naphthoquinone, and 2,5-dihydroxyacetophenones, amounting to more than 80 % of the total isolated chromophores in most cases. In lignin-free cellulosics, these three compounds can thus be regarded as key chromophores. The prevalence of these molecules is due to both exceptionally strong resonance stabilization, as reflected in delocalized double bonds, and their ready reformation from carbohydrate degradation products by recondensation reactions. The findings that (a) most chromophores in lignin-free cellulosic materials belong to only three compound classes and that (b) three chromophore compounds make up the bulk of the chromophore mixtures are foundational for future bleaching research: Based on this knowledge, specific searches for optimized bleaching conditions can now concentrate on these compounds and still cover the vast majority of chromophores.

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Section: Resultsmentioning

confidence: 99%

Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in cellulosics, XII

et al. 2015

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“…As we will discuss below, this compound presents enhanced reactivity relative to 1 . Treatment of 15 with dimethyl sulfoxide (DMSO) and acetic anhydride produced stable π‐delocalised sulfur‐ylide 3 in 50 % yield , . Reduction of this ylide by zinc powder in acetic anhydride (catalytic amount of trimethylamine) resulted in the formation of thio‐substituted aromatic compound 5 .…”

Section: Resultsmentioning

confidence: 99%

A Ring‐Distortion Strategy from Marine Natural Product Ilimaquinone Leads to Quorum Sensing Modulators

et al. 2018

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We report herein a ring‐distortion strategy applied to marine natural substances ilimaquinone and 5‐epi‐ilimaquinone. A chemically diverse library of molecules was synthesised that included rearrangements of the sesquiterpene moiety and original reorganisations of the quinone ring. Chemoinformatic analyses evaluated the rise of structural diversity and the exploration of chemical space. Some focussed biological activities of this library were also investigated; quorum sensing activity of Vibrio harveyi was envisaged and some of the new compounds were shown to be good quorum sensing inhibitor candidates, whereas others were activators. Toxicities were also evaluated and some products showed micromolar activities against human umbilical vein endothelium, human hepatocellular carcinoma and human lung carcinoma (A549) cells.

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“…From DHBQ, a bis(sulfonium ylide) (8) was formed, which resulted from a coupling of the chromophore with DMSO on both ''sides'' of the DHBQ molecule; and naphthoquinone derivative 7 provided the analogous mono(sulfonium ylide) 9 ( Fig. 4) (Rosenau et al , 2004b. These sulfonium ylides are extremely stable compounds that in most cases precipitate out of the reaction mixtures as bright yellow, crystalline precipitates (fine needles).…”

Section: Attempted Acylation/alkylation Of Dhbq In the Presence Of DImentioning

confidence: 99%

Pitfalls in the chemistry of cellulosic key chromophores

et al. 2018

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The chemistry of cellulosic key chromophores is challenging because of the usually very low concentration of the colored compounds in realworld cellulosic matrices. It offers many surprises and positive outcomes; unfortunately there are also pitfalls and disappointments. This report discusses eight examples or surprising chemistry out of the realm of cellulosic key chromophores. The reactions have either taken unforeseen paths or provided unexpected products. The reaction mechanisms of the ''strange'' processes are described and the products are comprehensively analytically characterized. Given that the seemingly obvious approaches have failed, alternatives for obtaining the desired products are provided, wherever possible.Hubert Hettegger and Hassan Amer have contributed equally to this work.

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Sulfonium ylides derived from 2-hydroxy-benzoquinones: crystal and molecular structure and their one-step conversion into Mannich bases by amine N-oxides

Cited by 12 publications

References 7 publications

Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in cellulosics, XII

Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in cellulosics, XII

A Ring‐Distortion Strategy from Marine Natural Product Ilimaquinone Leads to Quorum Sensing Modulators

Pitfalls in the chemistry of cellulosic key chromophores

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