Dicarbomethoxycarbene. A Laser Flash Photolysis Study

Wang, Jen-Lung; Toscano, John P.; Platz, Matthew S.; Nikolaev, V. A.; Popik, Vladimir V.

doi:10.1021/ja00125a007

Cited by 58 publications

(53 citation statements)

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“…ylides. The ''ylide probe technique'', introduced by Platz and Jackson, [165] was applied to ethoxycarbonyl carbene, [166] bis(methoxycarbonyl)carbene (157), [167] and thio analogues, [68c] focusing on carbene lifetimes and intermolecular reactions. LFP of diazo ketones 182 (R ϭ H, Me, iPr, tBu) in the presence of pyridine or acetone showed that the yields of the presumed ylides decrease with increasing bulk of R. [168] Toscano suggested that scavengeable carbonyl carbenes 183 arise from s-E-182 whereas excited s-Z-182 produces ketene 185 by a concerted route (Scheme 28).…”

Section: Laser Flash Photolysis (Lfp)mentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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The conversion of α‐diazo ketones into ketenes, and products derived therefrom, was discovered by Wolff in 1902. Major applications of the Wolff rearrangement, such as the Arndt−Eistert reaction (homologation of carboxylic acids) and the ring contraction of cyclic ketones, have been with us for some while. Nevertheless, substantial progress has been made recently. The reaction mechanism has been explored by means of matrix isolation, time‐resolved spectroscopy, and computation. Full retention of configuration of the migrating group has been established by using enantioselective chromatography. The Arndt−Eistert reaction has witnessed a renaissance in the field of natural products, in particular β‐amino acids and β‐peptides. Ring‐contracting Wolff rearrangements and ketene cycloadditions have been applied in syntheses of increasingly complex, biologically active target molecules. These accomplishments, as well as unsolved problems, are addressed in the present review. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Section: Laser Flash Photolysis (Lfp)mentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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“…3 Jones argued that the cyclopropanes obtained by photolysis of methyl diazomalonate derived both from the conventional carbene addition and from cycloaddition of the excited-state of the diazo compound to the alkene, followed by its decomposition to give alkenes of mixed stereochemistry. 2 We thus consider here whether an excited-state of compounds 2-4 might be involved in the cyclohexene insertion product 6.…”

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confidence: 99%

S,C-Sulfonium Ylides from Thiophenes: Potential Carbene Precursors

2007

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Carbenes remain important and intriguing reactive intermediates in organic chemistry despite years of study for many reasons, among them the access they provide to unusual product compounds, their differing chemistry depending on spin state, and their mechanistic complexity. Photochemical precursors to carbenes, such as diazo compounds and diazirines, are often favored, because they can yield carbenes by photolysis at low temperatures and can be used for laser flash photolysis experiments. However, because these nitrogenous precursors have been shown to undergo reactions in their excited states that mimic chemistry expected from the carbene itself, there is demand for alternative practical precursors. In this Communication, we report the use of S,C-sulfonium ylides 1-4 as photochemical carbene precursors, as illustrated in Scheme 1 for compound 4.The choice of compounds 1-4 as potential precursors to dicarbomethoxycarbene for this study was driven by two considerations. First S,C-ylides of malonates are known to be stable and easy to prepare, at least in part because of the electron withdrawing groups that delocalize the formal negative charge. Second, by generating dicarbomethoxycarbene 1-3 for the proof-of-concept work of showing carbene generation, we believed we could distinguish between reactions of the carbene and a potential excited state Wolfflike rearrangement that might yield a ketene derivative. Such 1,2shifts have been demonstrated repeatedly for nitrogenous carbene precursors that are subject to 1,2 hydrogen shifts or carbon shifts to relieve ring strain. [4][5][6][7][8][9][10]

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“…The decomposition of low‐molecular‐weight diazoesters and the reactions of the resulting carbenes are well described . Depending on the substituents of the C atom bearing the diazo group, the formed carbene can be either in the triplet or the singlet state, resulting in reactions with C−H bonds through different mechanisms .…”

Section: Methodsmentioning

confidence: 99%

Malonic Acid Diazoesters for C−H Insertion Crosslinking (CHic) Reactions: A Versatile Method for the Generation of Tailor‐Made Surfaces

Kotrade¹,

Rühe²

2017

Angewandte Chemie

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A simple and versatile method for the modification of a broad spectrum of surfaces with thin polymer films through the thermally or photochemically induced generation of surface‐attached polymer networks is reported. The system is based on copolymers containing diazomalonate groups, which can be activated by heat or light. To this end, the copolymers are deposited from solution onto solid substrates by standard techniques of thin‐film deposition (spin coating, dip coating). Upon activation the diazomalonate group decomposes and forms a carbene, which induces C−H insertion crosslinking (CHic) reactions. In the course of this process network formation and covalent surface attachment occur at the same time. The crosslinking process proceeds very rapidly, especially when the carbenes generated in the activation process cannot undergo Wolff‐rearrangement. The presented system can be used for the generation of a wide range of polymer layers and microstructures on a broad spectrum of surfaces.

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Dicarbomethoxycarbene. A Laser Flash Photolysis Study

Cited by 58 publications

References 0 publications

100 Years of the Wolff Rearrangement

100 Years of the Wolff Rearrangement

S,C-Sulfonium Ylides from Thiophenes: Potential Carbene Precursors

Malonic Acid Diazoesters for C−H Insertion Crosslinking (CHic) Reactions: A Versatile Method for the Generation of Tailor‐Made Surfaces

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