Push-Pull Olefins from Bis(Forkamidinium) Ethers

Maas, Gerhard; Feith, Bernhard

doi:10.1080/00397918408059636

Cited by 16 publications

(4 citation statements)

References 10 publications

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“…This arrangement promotes the π delocalization and the intramolecular charge transfer from the electron‐donating groups (“push” terminus) to the electron‐withdrawing groups (“pull” terminus) thus effecting both the molecular structure [e. g. central double bond elongation, [1] lowering of its rotational barrier] [2,3] and the physical‐chemical properties of the compounds [e. g. existence of strong charge‐transfer absorption bands, [4] large dipole moments, [5] and high hyperpolarizabilities] [6,7,8] . As a number of theoretical and experimental investigations assessed, [9–28] the form that better describes a push‐pull alkene is the zwitterion D (Figure 1), characterized by a strong charge transfer, large molecular dipole and quadrupole moments and, consequently, high polarization. These features make push‐pull alkenes particularly reactive with nucleophilic and electrophilic species and therefore these compounds represent versatile building blocks for the synthesis of (hetero)cycles.…”

Section: Introductionmentioning

confidence: 99%

One‐Pot Synthesis and Antiproliferative Activity of Highly Functionalized Pyrazole Derivatives

et al. 2022

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A series of highly functionalized pyrazole derivatives has been prepared by a one‐pot, versatile and regioselective procedure. Pyrazoles 1–29 were tested in cell‐based assay to assess their antiproliferative activity against a panel of tumour cells. Additionally, the cytotoxicity of prepared compounds was evaluated against normal human fibroblasts. The antiproliferative activity of the synthesized molecules emerged to be affected by the nature of the substituents of the pyrazole scaffold and derivatives 21–23 proved to inhibit the growth of melanoma and cervical cancer cells. Compound 23 was identified as the most active derivative and docking simulations predicted its ability to interact with estrogen receptors.

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Section: Introductionmentioning

confidence: 99%

One‐Pot Synthesis and Antiproliferative Activity of Highly Functionalized Pyrazole Derivatives

et al. 2022

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“…Elimination of pyridine gives the thermodynamic product DIDMAP (−60 kJ mol −1 ). Maas reacted DIPy with the monoanions of several geminal CH-diacids which led to ring-opening of the pyridinium moiety under the formation of a double bond with the former Py-C2 (26,36,37). Only select methylene-active nucleophiles (e.g.…”

Section: Main Textmentioning

confidence: 99%

Diiminium Nucleophile Adducts are Stable and Convenient Lewis Superacids

Bormann

Ward

Bergmann

et al. 2023

Preprint

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Strong Lewis acids are essential tools for a manifold of chemical procedures that aim to react weakly basic centres but their scalable deployment is severely limited by their costs and safety concerns. We report that dicationic relatives of guanidinium can be conveniently synthesised in a two-step one-pot procedure from tetramethylurea. Triflic anhydride is used to generate an isouronium intermediate. Substitution of the bound triflate with pyridines yield the dicationic tetramethyldiiminium bis(triflate) nucleophile adducts (TMDINu). Their proposed diiminium character is demonstrated by substituting pyridine from the corresponding adduct with other nucleophiles. The observation of a chelation effect in the 2,2’-bipyridine adducts supports Lewis acidic character of the diiminium π-system and flexibility towards accepting another bond. High fluoride, hydride, and oxide affinities are demonstrated, leading to their classification as soft and hard Lewis superacids. An example reaction is reported which shows that the tetramethyldiiminium bis(triflate) pyridine complex (TMDIPy) is more effective than conventional reagents in the activation of electron-poor amines for amide couplings.

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“…Elimination of pyridine gives the thermodynamic product DIDMAP (−60 kJ mol −1 ). Maas reacted DIPy with the monoanions of several geminal CH-diacids which led to ring-opening of the pyridinium moiety under the formation of a double bond with the former Py-C2 (25,35,36). Only select methylene-active nucleophiles (e.g.…”

Section: Main Textmentioning

confidence: 99%

Diiminium Nucleophile Adducts are Stable and Convenient Lewis Superacids

Mulks

Ward

Bergmann

et al. 2022

Preprint

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Strong Lewis acids are essential tools for a manifold of chemical procedures that aim to react weakly basic centres but their scalable deployment is severely limited by their costs and safety concerns. We report that dicationic relatives of guanidinium can be conveniently synthesised in a two-step one-pot procedure from tetramethylurea. Triflic anhydride is used to generate an isouronium intermediate. Substitution of the bound triflate with pyridines yield the dicationic tetramethyldiiminium bis(triflate) nucleophile adducts (TMDINu). Their proposed diiminium character is demonstrated by substituting pyridine from the corresponding adduct with other nucleophiles. The observation of a chelation effect in the 2,2’-bipyridine adducts supports Lewis acidic character of the diiminium -system and flexibility towards accepting another bond. High fluoride, hydride, and oxide affinities are demonstrated, leading to their classification as soft and hard Lewis superacids. An example reaction is reported which shows that the tetramethyldiiminium bis(triflate) pyridine complex (TMDIPy) is more effective than conventional reagents in the activation of electron-poor amines for amide couplings.

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Push-Pull Olefins from Bis(Forkamidinium) Ethers

Cited by 16 publications

References 10 publications

One‐Pot Synthesis and Antiproliferative Activity of Highly Functionalized Pyrazole Derivatives

One‐Pot Synthesis and Antiproliferative Activity of Highly Functionalized Pyrazole Derivatives

Diiminium Nucleophile Adducts are Stable and Convenient Lewis Superacids

Diiminium Nucleophile Adducts are Stable and Convenient Lewis Superacids

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