Synthesis and Reactions of Diazoketones

Arora, Ritu; Kashyap, Kriti; Mittal, Anshika; Kakkar, Rita

doi:10.1080/00304948.2019.1569409

Cited by 14 publications

(8 citation statements)

References 175 publications

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“…“Saturated” electrophilic singlet carbenes ( 1 ), endowed with an empty p-orbital on the formally sp 2 -hybridized divalent and neutral carbon atom, are known to accept an electron pair from heteroatom-containing moieties (e.g., 2 ) to form the corresponding ylides ( 3 ) (Scheme ). − These carbene-derived ylides have proven to be of considerable synthesis value, − and in many instances, they have been directly observed and spectroscopically characterized. − The structurally different “unsaturated” alkylidenecarbenes ( 4 ), which feature an sp-hybridized carbon atom attached to only one substituent by a double bond, prefer singlet ground states and are electrophilic in nature (Scheme ). − As expected, carbenes such as 4 also form ylides 5 by accepting an electron pair in their vacant p-orbital from appropriate nucleophilic donors ( 2 ) (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Detection of Ylide Formation between an Alkylidenecarbene and Acetonitrile by Femtosecond Transient Absorption Spectroscopy

Sarkar

Bai

et al. 2021

J. Am. Chem. Soc.

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Femtosecond laser flash photolysis of 3-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-ylidene)tetrahydrofuran produces singlet 3-oxacyclopentylidenecarbene which reacts with acetonitrile solvent to form an ylide. This is the first direct detection of ylide formation by an alkylidenecarbene. This new type of ylide was observed to have a broad absorption band in the visible region with λ max ∼450 nm and a lifetime of ∼13.5 ps. As with other "conventional" carbenes (the divalent carbon atom is separately bound to two substituents), this ylide formation method could be also useful for detecting alkylidenecarbenes, especially those that do not absorb at wavelengths suitable for direct observation. Furthermore, the mechanisms by which 3-oxacyclopentylidenecarbene forms the ylide and the overall favorability of ylide formation, vis-a-vis ring expansion of the carbene to strained 3-oxacyclohexyne, were supported by results from density functional theory calculations.

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Section: Introductionmentioning

confidence: 99%

Detection of Ylide Formation between an Alkylidenecarbene and Acetonitrile by Femtosecond Transient Absorption Spectroscopy

Sarkar

Bai

et al. 2021

J. Am. Chem. Soc.

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“…The main reactivity pattern of α-diazoketones and, in particular, azibenzil 11 ( Scheme 5 ), which we used as a model compound, includes elimination of dinitrogen and formation of highly reactive carbenes. 16 The reactions can be induced thermally, photochemical, or catalytically (acids, heavy metal oxides, and salts). The synthetically useful and well-studied reaction path includes the formation of carbene, its rearrangement into ketene, and the reaction with a nucleophile (e.g., water, alcohol, or amine); the overall transformation known as Wolff rearrangement ( Scheme 5 ).…”

Section: Resultsmentioning

confidence: 99%

“…The main reactivity pattern of α-diazoketones and, in particular, azibenzil 11 (Scheme ), which we used as a model compound, includes elimination of dinitrogen and formation of highly reactive carbenes . The reactions can be induced thermally, photochemical, or catalytically (acids, heavy metal oxides, and salts).…”

Section: Resultsmentioning

confidence: 99%

Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis

et al. 2021

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Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (−COCN 2 −) attached to position 5′ or 6′ of the pendant phenyl rings. For that, the mixture of 5′- or 6′-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones Ar 1 COCN 2 Ar 2 . The high performance liquid chromatography (HPLC) separation gave four individual regioisomers of Ar 1 COCN 2 Ar 2 . Photolysis of the model compound—C 6 H 5 COCN 2 C 6 H 5 —in aqueous acetonitrile at pH 7.3 and under irradiation with 365 nm light provided diphenylacetic acid amide (Wolff rearrangement). However, under the same conditions, Ar 1 COCN 2 Ar 2 gave mainly α-diketones Ar 1 COCOAr 2 . The migration ability of the very bulky dye residues was low, and the Wolff rearrangement did not occur. We observed only moderate fluorescence increase, which may be explained by the insufficient quenching ability of diazoketone bridge (−COCN 2 −) and its transformation into another (weaker) quencher, 1,2-diarylethane-1,2-dione.

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“…Unfortunately, the inventors did not provide any information about the mechanism of photodeactivation of the inhibitor. It can be suggested that exposure to UV-light resulted in photolysis of diazo compound by releasing the N 2 and Wolff rearrangement [93][94][95] producing substances that are no longer active inhibitors of Pt-catalyst. Recently, Bluestar Silicones France SAS patented a photoactivatable inhibiting system for silicone hydrosilylation curing 99 .…”

Section: Other Photoactive Inhibitorsmentioning

confidence: 99%

Photocatalyzed Hydrosilylation in Silicone Chemistry

Radchenko

Ganachaud

2022

Ind. Eng. Chem. Res.

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Hydrosilylation is widely used in silicone chemistry to crosslink formulations so as to generate elastomer materials. Most often, heat is the easiest way to activate a platinum catalyst that proceeds to reaction, but photoirradiation is an alternative way to promote hydrosilylation in a fast and mild way. The open and patent literatures dealing with lightinduced hydrosilylation are exhaustively reviewed here. First, various promoters, including metal (photo)catalyst, co-catalysts and inhibitors, are systematically described. Some kinetics provided by the very few available academic papers are disclosed as well. Throughout the review, proposed applications, mainly in coatings, are reported, whereas potential applications in 3D printing are specifically disclosed as a separate final chapter. Prospects about the pros

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Synthesis and Reactions of Diazoketones

Cited by 14 publications

References 175 publications

Detection of Ylide Formation between an Alkylidenecarbene and Acetonitrile by Femtosecond Transient Absorption Spectroscopy

Detection of Ylide Formation between an Alkylidenecarbene and Acetonitrile by Femtosecond Transient Absorption Spectroscopy

Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis

Photocatalyzed Hydrosilylation in Silicone Chemistry

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