Naphthalene 1,4-endoperoxide

The benzo-derivative 16 is accessible through 1,4-dimethylnaphthalene, which on singlet oxygenation leads to the thermally labile naphthalene-1,4-endoperoxide. This endoperoxide expels singlet oxygen at ca. 10 °C, but diimide reduction below 0 °C in MeOH affords the stable dihydro derivative 16 (Eq. 11). 

Naphthalene endoperoxides have been synthesized with methyl groups located at the 1,4-, 1,8-, 1,2,4-, 1,4,5-, 1,2,3,4-positions, and 1,2,3,4,5,6,7,8-positions in good yield after recrystallization of 58%, 88%, 93%, 54%, 83%, and 69%, respectively [48, 49]. The C—O bond formation preferably takes place at aryl sites bonded by the methyl groups. The stabilities of the endoperoxides were greater with increased numbers of methyl groups on naphthalene [at 25 °C in CDC13, compare... 

Martinez, G.R., Ravanat, J.-L., Medeiros, M.H.G., Cadet, J. and Di Mascio, P. (2000) Synthesis of a naphthalene endoperoxide as a source of lsO-labeled singlet oxygen for mechanistic studies. Journal of the American Chemical Society, 122 (41), 10212-10213. 

The CL properties were investigated in detail to assess possible analytical uses. To obtain the calibration curves for 02, water-soluble naphthalene endoperoxide (NEP) which thermally releases 02 at a constant concentration level was synthesized and used instead of the Na0Cl-H202 reaction. As shown in Fig. 2, the calibration curves for 02 were obtained as the function of the NEP concentration at 25 C. In the case of r-MSVP, linearity was shown over the concentration range of 2xl0 -lxl0 M and the lower limit of detection was 5x10 M which were superior to those of r-MVP. 

As discussed in Section II.A.4, photooxygenation of l-aryl-2-methylpropenes in solution proceeds slowly, and affords a complex mixture of products arising mainly from [4 + 2] or [2 + 2] addition to the double bond. The ene pathway is less favourable or even absent. For example, -dimethylstyrene (20) affords the ene adduct in approximately 20% yield, benzaldehyde (from a [2 - - 2] pathway), and mainly two diastereomeric di-endoperoxides (from a [4-1-2] pathway) in a 2/1 ratio (Scheme 48). Similarly, for l-(2-methylpropenyl)naphthalene (137), the 1,4-endoperoxide is mainly formed. ... 

Voluminous studies have been made to distinguish the reactivity of singlet oxygen, triplet oxygen, and electron transfer-generated superoxide (228). For example, while superoxide gives both endoperoxide and side chain oxidation of 1,4-dimethyl-naphthalene, eq. 73 (229),... 

The photooxide of naphthalene (74) on treatment with triphenylphosphine is converted to naphthalene 1,2-oxide (45).40 The photooxide of anthracene (75) is converted to syw-anthracene[4a,10 9,9a]diepoxide (76) in 78% yield by means of an interesting photochemical rearrangement.41 The endoperoxide of... 

Reaction of 102 with a water-soluble 1,4-disubstituted naphthalene (14) leads to a 5,8-endoperoxide (16), in addition to the 1,4-endoperoxide (15) which is normally obtained as the exclusive product in such reactions (in the absence of methyl groups at position 6, 7 or 8).211 Fonnation of the 5,8-isomer is probably due to the effect of steric hindrance of the bulky substituents impairing the approach of102 to the more crowded... 

Tetradehydrodianthracene undergoes 4 + 2-cycloaddition with electron-deficient dienes such as 1,2,4,5-tetrazines.263 The Diels-Alder reactions of [3.3 ortho-anthracenophanes witli A-(p-nitro, chloro, or methoxy-substituted phenyl)malehnides yield approximately equal quantities of inside and outside adducts.264 The photooxidation of bulky water-soluble 1,4-disubstituted naphthalenes with singlet oxygen yields both the expected 1,4- and the unexpected 5,8-endoperoxides.265... 

Wasserman, H.H. and Larsen, D.L. (1972) Formation of 1,4-endoperoxides from the dye-sensitized photo-oxygenation of alkyl-naphthalenes. Journal of the Chemical Society, Chemical Communications, (5), 253-254. 

Even in the case of simple aromatic dopants (naphthalene, anthracene, pyrene), fluorescence intensity is found to decrease with successive laser pulses and/or increasing laser fluence. The decrease may be ascribed to thermal desorption of the dopant, as indicated by Fukumura et al. [62], and/or to photooxidation/degradation of the dopants. In the present case, film transmission decreases in parallel with the dopant fluorescence, thus indicating the formation of photoproducts that absorb stronger than the precursor. (The photoproduct(s) are not detected in the fluorescence experiments, evidently because of its (their) low emission yield). NapH and related compounds are known to generate (Ag) efficiently [81]. This has a long lifetime within polymers and it can attack the aromatic to form the corresponding endoperoxide (Nap-02). Such processes have been shown to occur in related polymer systems. 

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