Wavelength-Dependent Photochemistry of Diazo Meldrum's Acid and Its Spirocyclic Isomer, Diazirino Meldrum's Acid:  Wolff Rearrangement versus Isomerization

Bogdanova, Aneta; Popik, Vladimir V.

doi:10.1021/ja029528p

Cited by 32 publications

(29 citation statements)

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“…It is interesting that thermolysis carried out in more polar reaction media (MeOH, 40°C) in practice gave the diazo compound 140a quantitatively. [101] Moreover, the diazirine 139a rapidly turns into the diazo isomer 140a in thermal fashion only in solution, remaining unchanged over several months in crystalline form. [102] The results obtained were confirmed by calculations relating to the potential energy barrier to the thermal isomerization of the diazirine to the diazo compound in the gas phase (about 30-37 kcal mol -1 ).…”

Section: Spirocyclic Dialkyl Diazirine-33-dicarboxylatesmentioning

confidence: 99%

“…[116] Numerous data on the behavior of cyclic diazodicarbonyl compounds have given new impetus to a revision of the properties of their linear analogues (Scheme 56). [80,101] It has been reported that irradiation of the diazomalonic ester 136 (UV: 251, 344 nm) at room temperature leads to the formation of two main products: the methoxymalonate 137 (elimination of nitrogen) and the diazirine 135 (isomerization, UV: 244, 291 nm).…”

Section: Diazodiestersmentioning

confidence: 99%

“…[98] The mechanism of photolysis product formation in this case, as a whole, also corresponds with that for the cyclic diazo-Meldrum's acid (140a). [80,101] …”

Section: Diazodiestersmentioning

confidence: 99%

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Valence Isomerization between Diazo Compounds and Diazirines

Korneev

2011

Eur J Org Chem

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Diazo compounds and diazirines have been separately studied in detail and are widely used in research and for applied purposes. Although the mutual isomerization of these compounds was discovered 50 years ago, it has still been only modestly investigated. Meanwhile, this type of mutual transformation has to be taken into account on every occasion when one of these compounds is used or investigated. This review discusses all main cases of mutual isomerization between diazo compounds and diazirines with the goal of providing an impulse for its rational application, as well as describing the isomerism.

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Section: Spirocyclic Dialkyl Diazirine-33-dicarboxylatesmentioning

confidence: 99%

Section: Diazodiestersmentioning

confidence: 99%

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Valence Isomerization between Diazo Compounds and Diazirines

Korneev

2011

Eur J Org Chem

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“…The direct irradiation (λ > 210 nm) of diazodiketones 1 gives rise to accumulation of one of their upper singlet excited states 1 ( 1 )* [13,15,18,20,49–51] which turn into usual Wolff rearrangement products, i.e., highly reactive oxoketenes 6 (Scheme 2, reaction I). The intermediate ketenes 6 react with H 2 O or MeOH present in the reaction mixture to give 2-oxocarboxylic acid 4a or esters 5a–c .…”

Section: Resultsmentioning

confidence: 99%

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

Rodina¹,

Azarova²,

Medvedev³

et al. 2018

Beilstein J. Org. Chem.

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The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С–Н bond of THF, producing the associated N-alkylhydrazones in yields of up to 63–71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90–97% yield.

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“…The position of these absorbance bands is virtually independent from the polarity of the solvents used, and thus does not allow a confident Scheme 1 assignment to the relevant transitions. However, by analogy with other diazocarbonyl compounds [13 -16], these absorptions can be evidently attributed to p -p* and n -p* electronic transitions, respectively (see also [17] (Schemes 2 and 3). Irradiation was carried out in a quartz vessel with UV light of a medium-pressure Hg lamp (l > 210 nm) under an O 2 -free atmosphere until complete disappearance of 1a or 1b in the reaction mixture (by TLC; normally 1.5 -2 h).…”

mentioning

confidence: 86%

Photochemical Reactions of Regioisomeric 2,2‐Dimethyl‐5,5‐diphenyl‐ and 5,5‐Dimethyl‐2,2‐diphenyl‐Substituted Diazo Ketones of a Tetrahydrofuran Series

Rodina

Malashikhin

Galkina

et al. 2009

Helvetica Chimica Acta

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The principal direction of conventional photolysis of the regioisomeric 2,2-dimethyl-5,5-diphenyland 5,5-dimethyl-2,2-diphenyl-substituted 4-diazodihydrofuran-3(2H)-ones 1a and 1b, respectively, is the Wolff rearrangement, while other photochemical processes, which are giving rise to the formation of CÀH-insertion, 1,2-alkyl-or -aryl-shifts, as well as H-atom-abstraction products occur to a much lower degree (Schemes 2 and 3). The ratio of similar reaction products from both regioisomers 1a and 1b is essentially independent of their structure, and a substantial effect of the relative position of the Ph and diazo group to each other on the yield of CÀH-insertion products does not occur. Based on stereochemical considerations, the Wolff rearrangement of diazodihydrofuran-3(2H)-ones apparently proceeds in a concerted manner, whereas the appearance in the reaction mixture of 1,2-shift and H-atomabstraction products points to the parallel generation during photolysis of singlet and triplet carbenes (Schemes 4 and 5).1. Introduction. -Direct photolysis of cyclic diazocarbonyl compounds usually proceeds with elimination of N 2 and formation of the Wolff rearrangement products (for reviews, see [1 -6]). Thus, light-induced decomposition of diazo ketones A with 2,2,5,5-tetraalkyl substituents at the heterocycle (R ¼ Me, Et, and others) by shortwavelength UV light (l > 210 nm) in dioxane solution, as a rule, gives rise to oxetanecarboxylic acids B or their derivatives (Scheme 1) in yields of up to 90 -95% [7].On the other hand, it was recently established [8] that photolysis of tetraphenylsubstituted diazo ketone A (R ¼ Ph) in THF solution, besides ordinary Wolffrearrangement products C, furnished the adduct D of diazo ketone A with THF (Scheme 1). The latter can be considered as the product of the insertion of the terminal N-atom of the diazo group into the HÀC(2) bond of THF. The revealed transformation of tetraphenyl-substituted diazo ketone A is apparently the first example of the photolysis of diazo ketones which proceeds with the retention of both N-atoms of the diazo group in the reaction products [9] [10].

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Wavelength-Dependent Photochemistry of Diazo Meldrum's Acid and Its Spirocyclic Isomer, Diazirino Meldrum's Acid: Wolff Rearrangement versus Isomerization

Cited by 32 publications

References 13 publications

Valence Isomerization between Diazo Compounds and Diazirines

Valence Isomerization between Diazo Compounds and Diazirines

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

Photochemical Reactions of Regioisomeric 2,2‐Dimethyl‐5,5‐diphenyl‐ and 5,5‐Dimethyl‐2,2‐diphenyl‐Substituted Diazo Ketones of a Tetrahydrofuran Series

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