Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives

Yardımcı, Şengül Dilem; Kaya, Nihal; Balcı, Metin

doi:10.1016/j.tet.2006.07.103

Cited by 15 publications

(9 citation statements)

References 38 publications

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“…By this effect, the 1,3-diene structure is retained and subsequent Diels-Alder reactivity with 1 O 2 is obtained. This type of a domino (or, more correctly, a diene-transmissive sequence) photooxygenation process [45][46][47] requires an acceptor group at the terminal carbon (Acc = COOR, COOH, CHO) and can be easily performed as a one-pot process.…”

Section: Results With Terminal Polyene Estersmentioning

confidence: 99%

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Griesbeck

Kleczka

Kiff

et al. 2015

Pure and Applied Chemistry

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The primary chemical reactions of singlet molecular oxygen with polyunsaturated carotenoids are the focus of this research report. Model compounds that exhibit electronic properties and substituent pattern similar to natural carotenes, xanthophylls or apocarotenoids, respectively, were investigated with regard to photooxygenation reactivity. For dienes and trienes as substrates, high tandem reactivity was observed and hydroperoxy-endoperoxides were isolated as the secondary products of singlet oxygen reaction. The electronic gem-effect on the regioselectivity of the ene reaction is conserved also in vinylogous positions and thus appears to originate from a radical-stabilizing effect. In an attempt to combine different peroxide groups derived from natural products as a tool for new pharmaceutically active products, a dyade synthesis of an artemisinine-safranol with subsequent singlet oxygen addition was realized.

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Section: Results With Terminal Polyene Estersmentioning

confidence: 99%

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Griesbeck

Kleczka

Kiff

et al. 2015

Pure and Applied Chemistry

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“…However, many of them show remarkable stability. A few stable ones are shown in Scheme 12 (51,(55)(56)(57)(58)(59)(60)(61)(62)(63).…”

Section: Endoperoxidesmentioning

confidence: 99%

“…Moreover, substrate a-terpinene, 45 (Table 5, entry 3) was exclusively converted, after 5min irradiation, to the natural product ascaridole. The same substrate was also photooxygenated with [60]fullerene-linked silica gel as the heterogeneous catalyst. Under those conditions, the reaction afforded lower yield and required longer irradiation time (207).…”

Section: -Heterogeneous Sensitized Photooxidationsmentioning

confidence: 99%

Singlet Oxygen: Discovery, Chemistry, C₆₀‐Sensitization^†

Orfanopoulos

2021

Photochem & Photobiology

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This review article refers to the discovery of excited molecular oxygen, in particular on its lower singlet excited state ( 1 D g , 1 O 2 ). After a short report on singlet oxygen generation, the review is focused on the chemistry of this reactive species. Specifically, the three major reactions of 1 O 2 with unsaturated organic substrates, namely the [4 + 2] and [2 +2] cycloadditions as well as the ene reaction, are reviewed. The proposed mechanisms of these reactions, through the years, based on experimental and computational work, have been presented. Selected examples of singlet oxygen-synthetic applications are also mentioned. The [60]fullerene and fullereno-materials photosensitized oxidations in homogeneous, as well as in heterogeneous conditions, are also comprehensively discussed.Finally, the self-sensitized photooxidation of open cage fullerenes as well as fullerenes bearing oxidizable groups is reported.

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“…• acts as an oxidizing agent and reacts with a double bond to form hydroperoxides through the ene-reaction [24]. The rate of this reaction is expressed through a kinetic constant: the quenching constant (Kq).…”

Section: Ros/rns and Squalenementioning

confidence: 99%

“…SQ oxidation occurs in a dose dependent fashion and the different isomers are produced in the same percentages. During this reaction O 2 ● acts as an oxidizing agent and reacts with a double bond to form hydroperoxides through the ene-reaction [ 24 ].…”

Section: Ros/rns and Squalenementioning

confidence: 99%

Squalene: More than a Step toward Sterols

Micera

Botto²,

Geddo

et al. 2020

Antioxidants

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Squalene (SQ) is a natural triterpene widely distributed in nature. It is a metabolic intermediate of the sterol biosynthetic pathway and represents a possible target in different metabolic and oxidative stress-related disorders. Growing interest has been focused on SQ’s antioxidant properties, derived from its chemical structure. Strong evidence provided by ex vivo models underline its scavenging activity towards free radicals, whereas only a few studies have highlighted its effect in cellular models of oxidative stress. Given the role of unbalanced free radicals in both the onset and progression of several cardiovascular diseases, an in depth evaluation of SQ’s contribution to antioxidant defense mechanisms could represent a strategic approach in dealing with these pathological conditions. At present experimental results overall show a double-edged sword role of squalene in cardiovascular diseases and its function has to be better elucidated in order to establish intervention lines focused on its features. This review aims to summarize current knowledge about endogenous and exogenous sources of SQ and to point out the controversial role of SQ in cardiovascular physiology.

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Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives

Cited by 15 publications

References 38 publications

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Singlet Oxygen: Discovery, Chemistry, C₆₀‐Sensitization^†

Squalene: More than a Step toward Sterols

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Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives

Cited by 15 publications

References 38 publications

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Singlet oxygen and natural substrates: functional polyunsaturated models for the photooxidative degradation of carotenoids

Singlet Oxygen: Discovery, Chemistry, C60‐Sensitization†

Squalene: More than a Step toward Sterols

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Singlet Oxygen: Discovery, Chemistry, C₆₀‐Sensitization^†