Intermediates in the dye-sensitized photooxygenation of nitrones and hydrazones

Erden, İhsan; Griffin, Albert; Keeffe, James R.; Brinck‐Kohn, V.

doi:10.1016/0040-4039(93)89014-h

Cited by 15 publications

(14 citation statements)

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“…The functionalized nitrone 5a reacted with dimethyl acetylenedicarboxylate (DMAD) at room temperature and, by 1,3-dipolar cycloaddition, led to the hydroperoxy-2,3-dihydroisoxazole 11 in 90% yield. In refluxing C 6 H 6 compound 5a gave a mixture of products [ 9 (32%), 10 (33%), 12 (6%), and 13 + 15 (22%)] that were structurally similar to those previously obtained from thermally unstable hydroperoxynitrones …”

Section: Resultssupporting

confidence: 56%

“…This mixture was also obtained when the reaction was carried out in CH 2 Cl 2 at −20 °C. The low stability of 5c can be related to that observed for nitrones similarly substituted on the hydroperoxidic carbon …”

Section: Referencesmentioning

confidence: 88%

“…These results were especially surprising in light of the fact that the only previously reported hydroperoxynitrones were obtained by singlet oxygen oxygenation of some nitrones at −78 °C. The latter were characterized by 1 H NMR spectra recorded at −60 °C, since upon warming to room temperature they led to complex mixtures of compounds via cyclic peroxides …”

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Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

et al. 1996

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Section: Resultssupporting

confidence: 56%

Section: Referencesmentioning

confidence: 88%

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confidence: 99%

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Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

et al. 1996

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“…The hypothesis that cleavage compounds 8 and 9b could derive from an undetected thermally unstable nitrone should be rejected since no hydroperoxy nitrone previously reported showed a similar decomposition route. , …”

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confidence: 99%

Carbonyl Oxide Chemistry. 6.¹ N-(Hydroperoxyalkyl)keto Nitrones and α-Oxime Ether Hydroperoxides via Disubstituted Carbonyl Oxides and Oximes

1998

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“…reports the hydroperoxynitrones 17 prepared, which are the first examples of thermally stable compounds in the series 31. …”

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1-Alkoxy-2,3,7-trioxabicyclo[2.2.1]hept-5-enes: Bicyclic Monoperoxy Ortho Esters as Useful Synthons for Multifunctional Compounds

Scarpati¹,

Iesce²,

Cermola³

et al. 1998

Synlett

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IntroductionAlthough the 2,3,7-trioxabicyclo[2.2.1]hept-5-enes 2, usually known as furan endo-peroxides, were postulated by Schenck 1 in 1944 as unstable primary products formed when furans 1 were subject to sensitized or auto-sensitized photo-oxygenation, these peroxides were not isolated until 1980. 2 At that time our group carried out the dye-sensitized photooxygenation of furans substituted at C-3 with an electron-withdrawing group on the basis that delocalization of the π-electrons in the furan endo-peroxide structure by an electron-withdrawing substituent would ensure that the reactivity of this system lay between that of the monoozonides of cyclobutadiene derivatives and of the more stable ozonides of cyclobutene derivatives. 3 Thus, endo-peroxides 2 which were sufficiently stable to be isolated and characterized by analytical and spectral data were obtained (Scheme 1). 2 Successively, a systematic study on the reaction of singlet oxygen with furans substituted at C-2 and C-5 with aryls, 4 alkyls 5 or hydrogens 6 showed that the furan endoperoxides are formed in any case. However, the latter undergo thermal rearrangement by various pathways depending chiefly on the nature of the substituents at C-1 and C-4, 4-6 although the reaction conditions are equally important. 7 These endo-peroxides generally react with primary and secondary alcohols to give 2-alkoxy-5-hydroperoxy-2,5-dihydrofurans 3 (Scheme 1) or products which are believed to derive from these compounds. 2,5c Alternatively, they fail to add alcohols at all, as is the case with electron-deficient endo-peroxides 8,6a,6c whose behaviour confirms the addition pathway suggested. 5c Scheme 1In the present account, the authors wish to describe their recent progress concerning the reaction of singlet oxygen with 2-alkoxyfurans which leads to 1-alkoxy-2,3,7-trioxabicyclo[2.2.1]hept-5-enes 5 having a bicyclic monoperoxy ortho ester structure (Scheme 2). The dyesensitized photo-oxygenation of the parent 2-methoxyfuran (4a) was carried out several years ago by Gollnick et al. 5c in an extensive study on the addition of singlet oxygen to furans. However, this part of the subject was only touched on and the results were examined only superficially. Nevertheless, endo-peroxide 5a was identified by 1 H NMR spectrum recorded at -70 °C and at higher temperatures it gave only resinous material. Scheme 2 Synthetic EntryIn order to obtain more manageable 1-alkoxy-2,3,7-trioxabicyclo[2.2.1]hept-5-enes 5 than rather 5a, we performed dyesensitized photo-oxygenation at a low temperature (-20 or -60 °C) in CDCl 3 /CFCl 3 on 2-alkoxyfurans 4 substituted at C-3 and/or C-4 with electron-withdrawing groups and at C-5 with a phenyl substituent. [8][9][10] Then, in order to confirm the behaviour of the endo-peroxides 5 obtained, we extended the dye-sensitized photo-oxygenation to 2-alkoxyfurans variously substituted while working at a temperature range of -80 to -70 °C. [11][12][13][14] In any case the endo-peroxides 5, which are thermally less stable than those bearing aryls, ...

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Intermediates in the dye-sensitized photooxygenation of nitrones and hydrazones

Cited by 15 publications

References 3 publications

Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 6.¹ N-(Hydroperoxyalkyl)keto Nitrones and α-Oxime Ether Hydroperoxides via Disubstituted Carbonyl Oxides and Oximes

1-Alkoxy-2,3,7-trioxabicyclo[2.2.1]hept-5-enes: Bicyclic Monoperoxy Ortho Esters as Useful Synthons for Multifunctional Compounds

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Intermediates in the dye-sensitized photooxygenation of nitrones and hydrazones

Cited by 15 publications

References 3 publications

Carbonyl Oxide Chemistry. 5.1 Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 5.1 Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 6.1 N-(Hydroperoxyalkyl)keto Nitrones and α-Oxime Ether Hydroperoxides via Disubstituted Carbonyl Oxides and Oximes

1-Alkoxy-2,3,7-trioxabicyclo[2.2.1]hept-5-enes: Bicyclic Monoperoxy Ortho Esters as Useful Synthons for Multifunctional Compounds

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Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 5.¹ Nucleophilic Trapping Reaction with Aldo and Keto Oximes. Synthesis of Hydroperoxynitrones

Carbonyl Oxide Chemistry. 6.¹ N-(Hydroperoxyalkyl)keto Nitrones and α-Oxime Ether Hydroperoxides via Disubstituted Carbonyl Oxides and Oximes