Singlet oxygen naphthalenes

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). 

Photoreduction of m-dinitrobenzene is suppressed by nitric oxide and atmospheric oxygen Quenching by naphthalene, which also has been observed, does not necessarily imply a triplet excited reacting state, since quenching of the excited singlet by naphthalene would be an alternative possibility. 

Chiral metal complexes, aUylic alcohol epoxidation catalysis, 394-401 Chiral naphthalene derivatives, singlet oxygen cycloaddition, 271... 

FIGURE 10.29 Typical photoproducts observed (A) in the irradiation (A = 300 nm) in air of naphthalene and 1-methylnaphthalene adsorbed on silica and formed by a Type I electron transfer (superoxide) mechanism (Barbas et al., 1993) and (B) in the irradiation in air of acenaphthylene (A = 350 nm) adsorbed on silica formed by a Type II singlet oxygen mechanism (Barbas et al., 1994) (adapted from Dabestani, 1997). 

Methyl-substituted naphthalenes react with singlet oxygen,818 820 825 826 but the reactivity depends on the position of the substituents. Whereas 2-methylnaphthalene is... 

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),... 

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... 

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. 

I, 4-disubstituted naphthalene by singlet oxygen. Journal of the Chemical Society,... 

Ketone 8 and the naphthalene homologue can be generated in solution " from singlet oxygen addition to various alkylidenecycloproparenes (Section VLB.2). However, attempts to construct 87 from 5,7-dibromodibenzo[ ,c]cycloheptadienone were unsuccessful " and the only known condensed analogue is 88 that has been matrix isolated prior to photodecarbonylation". ... 

---