Generation of Singlet Oxygen from Fragmentation of Monoactivated 1,1-Dihydroperoxides

Abstract

The first singlet excited state of molecular oxygen (1O2) is an important oxidant in chemistry, biology, and medicine. 1O2 is most often generated through photosensitized excitation of ground state oxygen. 1O2 can also be generated chemically through the decomposition of hydrogen peroxide and other peroxides. However, most of these “dark oxygenations” require water-rich media associated with short 1O2 lifetimes, and there is a need for oxygenations able to be conducted in organic solvents. We now report that monoactivated derivatives of 1,1-dihydroperoxides undergo a previously unobserved fragmentation to generate high yields of singlet molecular oxygen (1O2). The fragmentations, which can be conducted in a variety of organic solvents, require a geminal relationship between a peroxyanion and a peroxide activated towards heterolytic cleavage. The reaction is general for a range of skeletal frameworks and activating groups and, via in situ activation, can be applied directly to 1,1-dihydroperoxides. Our investigation suggests the fragmentation involves rate-limiting formation of a peroxyanion that decomposes via a Grob-like process.

Gadolinium(III) Porpholactones as Efficient and Robust Singlet Oxygen Photosensitizers

“…In contrast to Pd II and Pt II complexes, Ln porphyrinates have been much less studied although some of them display oxygen‐sensitive phosphorescence with long lifetimes (up to 100 μs). In this work, the catalytic activity of Gd III complexes ( Gd‐1 – 4 ) was initially evaluated by photo‐oxygenation of diphenylisobenzofuran (DPBF), using UV/Vis spectroscopy to monitor the reaction process . As shown in Figure a, these Gd complexes can effectively lead to the decay of DPBF whereas Yb complexes are not reactive upon irradiation with white light (400–700 nm).…”

“…In this work, the catalytic activity of Gd III complexes (Gd-1-4)w as initially evaluated by photo-oxygenation of diphenylisobenzofuran (DPBF), using UV/Vis spectroscopy to monitort he reaction process. [30] As shown in Figure4a, these Gd complexes can effectively lead to the decay of DPBF whereas Yb complexes are not reactiveu pon irradiation with white light (400-700nm). Among Gd-1-4, Gd-4 displayed the highest reactivity when using either white (400-700 nm) or red (600-700nm) light irradiation, which is consistent with the order of 1 O 2 production (Gd-4 > Gd-3 > Gd-2 > Gd-1).…”

Endogenous Generation of Singlet Oxygen and Ozone in Human and Animal Tissues: Mechanisms, Biological Significance, and Influence of Dietary Components

“…Gem dihydroperoxide 57 may also be formed in an uncatalyzed reaction between H 2 O 2 and 1-hydroxyhydroperoxide 52 [ 80 , 81 ]. Hang et al [ 82 ] reported that some monosubstituted 1,1-dihydroperoxides undergo decomposition to produce singlet oxygen in high yield. A reaction of 57 with a gem diol may generate such monosubstituted 1,1-dihydroperoxide 58 as a precursor of singlet oxygen.…”

The Chemistry of Peresters

“…The substrates, easily generated through monoacylation of 1,1‐dihydroperoxides, undergo fragmentation in the presence of fluoride or alkoxide; the reaction can also be triggered by fluoride‐promoted desilylation of a trialkylsilylperoxide or by acylation or sulfonation of 1,1‐dihydroperoxides in the presence of excess base. A postulated mechanism involving an extremely low‐barrier Grob‐type fragmentation (Figure ) is supported by calculations and by the observation that the step associated with proton removal is rate limiting , …”