Aldehyde durch Formylierung von Grignard‐ und Organolithium‐Reagentien mit <i>N</i>‐Formylpiperidin

Oláh, George A.; Arvanaghi, Massoud

doi:10.1002/ange.19810931034

Cited by 20 publications

(4 citation statements)

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“…The starting materials 3, 4 were prepared according to literature procedures [21,22], 2,5-dipropoxyterephthaldialdehyde 5 from 1,4-dipropoxybenzene [23] by twofold bromination and Bouveault-reaction with butyl lithium and DMF [19,24]. The Heck-and Knoevenagel-reactions of 3 and (5) with styrene or benzaldehyde, respectively [25,26], gave the electron deficient DSBs 6i, 6k range of 100 nm.…”

Section: Synthesismentioning

confidence: 99%

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Stalmach

Detert²

2000

J. prakt. Chem.

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Poly(p-phenylenevinylene) and its derivatives are one of the preferred groups of materials for the use as emissive layer in organic polymer light emitting diodes [1 -4]. Several groups investigated the photochemistry and particularly the photophysical behaviour of these polymers in order to establish knowledge of the fundamental properties that are responsible for the efficiencies of the devices as well as their amelioration [3 -9]. However, the fact that the parent polymer is insoluble and intractable prevents its complete characterization so that systematic investigations on structure-property relationships are almost impossible. A part of this problem can be circumvented by the investigation of model compounds. This approach, the estimation of the properties of a polymer by investigation of oligomers as model compounds is widely used, especially in the field of conjugated polymers [10 -15].Oligo(phenylenevinylene)s are useful as model compounds for the corresponding polymers and as luminescent material in Organic Light Emitting Diodes (OLEDs). Herein, the synthesis and the electronic spectra of a series of substituted distyrylbenzenes (DSBs) with a great variety of position, number, and character of substituents is reported. In order to elucidate the influence of different substitution patterns on the absorption and emission spectra, electron donors like dimethylamino and alkoxy side chains, a well as electron withdrawing groups like sulfones or nitriles and combinations of them were studied. Electron-donating ether groups have been used extensively in the field of conjugated polymers, as they reduce the band gap and allow to attach solubilising side chains. Sulfones and nitriles on the other hand, are electron withdrawing, which is especially important for a balanced charge carrier injection into the emitting material in a LED [16,17] Abstract. The influence of substitution on the absorption and Luminescence spectra of oligo(phenylenevinylene)s has been studied using distyrylbenzene (DSB) as a model compound. The degree, character, and pattern of substitution was varied systematically, altering the electronic properties of the DSB, the wavelength of the emitted light could be tuned over a for the application of metals with higher work function as cathode [18]. To allow comparison of the influences of different substitution, the basic chromophore, DSB, remains unchanged. SynthesisSeveral reactions are suitable to synthesize 1,4-distyrylbenzenes with two identical styrene units. Besides aldol-type condensations like Knoevenagel and Siegrist, Heck and Wittig-Horner reactions are most versatile. For the latter one, the starting materials are terephthaldialdehydes or 1,4-bis(halomethyl)benzenes for the central ring and benzylic halides or benzaldehydes for the lateral units.The majority of the distyrylbenzenes investigated here (6a -h) was synthesized starting with the MichaelisArbusov reaction of easily accessible 1,4-bis(chloromethyl) benzenes [19] to bisphosphonates 1a, 1b followed by PO-activated olefination ...

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Section: Synthesismentioning

confidence: 99%

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Stalmach

Detert²

2000

J. prakt. Chem.

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“…As a consequence of the lower stability of this pyridyl‐type intermediate compared to a classical one,20 it is possible to install a second organometallic, thus giving unsymmetrical secondary or tertiary alcohols 17 21. However, the presence of the pyridyl moiety is not a strict requirement, as shown by Olah and Arvanaghi in the formylation of Grignards and organolithiums with N ‐formylpiperidine ( 18 ),22 Almost contemporarily, Nahm and Weinreb employed N ‐methyl‐ N ‐methoxy amides (Weinreb amides, 20 ), which upon addition of an organometallic reagent form the five‐membered intermediate 21 , thus facilitating the synthesis of ketones in a straightforward manner 7,8. Despite the versatility of the Weinreb amide reactions, full chemoselectivity has never been described for this protocol 8,23.…”

Section: Introductionmentioning

confidence: 99%

Increasing the Reactivity of Amides towards Organometallic Reagents: An Overview

2014

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The nucleophilic addition of carbon nucleophiles to amides has traditionally been a difficult task, both due to reactivity and selectivity problems. When successful, these processes would represent straightforward routes towards carbonyl‐type or amine compounds, depending on the fate of the generated tetrahedral intermediate. The direct addition of nucleophiles to amides for the preparation of ketones has been studied and applied to the syntheses of several natural products. On the other hand, the addition of nucleophiles to amides to obtain substituted amines represented a major challenge, and only scattered applications on particular substrates have appeared. Initial improvements were based on the activation of amides by introduction of particular substituents, such as in N‐methoxy amides (Weinreb amides) or electron‐withdrawing groups able to increase the carbon nucleophilicity. Although these strategies facilitate the introduction of nucleophiles, chemoselectivity issues arise when additional electrophilic moieties (i.e., carbonyls) are present, thus decreasing the versatility of the methods. In recent years, important advancements towards fully chemoselective methods have been realized. The capture of tetrahedral intermediates with acids generates highly electrophilic iminium species able to undergo chemoselective additions of various nucleophiles, thus accessing substituted amines. Alternatively, the in situ generation of an iminium triflate ion allows highly chemoselective additions of nucleophiles, yielding amines, ketones or ketimines. Also thioamides can be used as precursors of ketones or α‐substituted amines. The success of the above methodologies is further showcased by the application in various syntheses of natural products or biologically active molecules.

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“…Photo-induced SubstitutiveI ntroduction of the Aldoxime Functional Group to Carbon Chains:AFormal Formylation of Non-Acidic C(sp 3 ) À HB onds Shin Kamijo,* Go Takao,K aori Kamijo,Masaki Hirota, Keisuke Tao, and Toshihiro Murafuji Abstract: Ap hoto-induced substitutive introduction of an aldoxime functional group to carbon chains was achieved using photo-excited 4-benzoylpyridine as aC (sp 3 )ÀHb ond cleaving agent and arylsulfonyl oxime as an aldoxime precursor.T he non-acidic C À Hb onds in various substances, including cycloalkanes,e thers,a zacycles,a nd cyclic sulfides, were chemoselectively converted at ambient temperature under neutral conditions.T he present transformation is af ormal formylation of non-acidic C(sp 3 )ÀHb onds in asingle step.…”

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“…Va rious electrophilic formylating agents,i ncluding N-formylpiperidine and CO,h ave been developed. [3] At wo-step sequence,i nvolving alkylation of an ucleophilic 1,3-dithiane anion with alkyl halides and subsequent deprotection, is another option for introducing the formyl functional group (Scheme 1-2a). [4] Thet reatment of alkyl halides with AIBN/Bu 3 SnH/CO gas achieves radical formylation to furnish aldehydes (Scheme 1-2b).…”

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Photo‐induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non‐Acidic C(sp³)−H Bonds

Kamijo,

Takao,

Kamijo

et al. 2016

Angew Chem Int Ed

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A photo-induced substitutive introduction of an aldoxime functional group to carbon chains was achieved using photo-excited 4-benzoylpyridine as a C(sp(3) )-H bond cleaving agent and arylsulfonyl oxime as an aldoxime precursor. The non-acidic C-H bonds in various substances, including cycloalkanes, ethers, azacycles, and cyclic sulfides, were chemoselectively converted at ambient temperature under neutral conditions. The present transformation is a formal formylation of non-acidic C(sp(3) )-H bonds in a single step.

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Aldehyde durch Formylierung von Grignard‐ und Organolithium‐Reagentien mit N‐Formylpiperidin

Cited by 20 publications

References 9 publications

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Increasing the Reactivity of Amides towards Organometallic Reagents: An Overview

Photo‐induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non‐Acidic C(sp³)−H Bonds

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Aldehyde durch Formylierung von Grignard‐ und Organolithium‐Reagentien mit N‐Formylpiperidin

Cited by 20 publications

References 9 publications

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

Increasing the Reactivity of Amides towards Organometallic Reagents: An Overview

Photo‐induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non‐Acidic C(sp3)−H Bonds

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Photo‐induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non‐Acidic C(sp³)−H Bonds