Photochemical aerobic oxidation of sulfides to sulfoxides: the crucial role of wavelength irradiation

Abstract

The sulfoxide moiety is recognized as one of the most important groups in organic and medicinal chemistry. Many efforts worldwide focus on developing novel and sustainable protocols, accessing sulfoxide-containing molecules....

A sustainable photochemical aerobic sulfide oxidation: access to sulforaphane and modafinil

“…Again, this is a slightly decreased reaction time compared with our previous studies (2 h vs. 3 h). 26 Quantitative formation of the desired sulfoxide was also obtained when GVL or water was used as the solvent (Table 2, entries 3 and 5); however, lower yields were obtained upon isolation (60% and 68%, respectively). Furthermore, GVL and water might pose difficulties when the catalyst-free protocol is used in the pharmaceutical industry.…”

“…Indeed, 2-Me-THF was the solvent of choice, reducing the reaction time at the same time, in comparison with our previous results. 26…”

“…25 Recently, we reported a mild, green and chemoselective direct photochemical aerobic oxidation of sulfides to the corresponding sulfoxides. 26 Our experience in developing operationally simple and safe protocols easily applied in industrial scale productions 27 led us to upgrade our methodology to a sustainable and industry-friendly protocol. Herein, we report environmental, novel, green and sustainable protocols for the oxidation of sulfides using a mild oxidant, such as molecular oxygen, in the presence of a low-cost commercially available photocatalyst.…”

Photochemical Aerobic Upcycling of Polystyrene Plastics to Commodity Chemicals

“…36 Also, anthraquinone is known to participate in HAT processes, 23 while it can also generate singlet oxygen. 32 Fluorescent quenching studies were then performed (Figure 1). After irradiation of anthraquinone (2b) (1 mM in MeCN) at 358 nm, its fluorescence was measured at 404 nm.…”

“…Since our control experiments showed that singlet oxygen could also play a role in the process, a secondary pathway is also proposed (Scheme 8, B). The triplet state anthraquinone is capable of generating singlet oxygen, 32 leading to the mechanism proposed in Scheme 8, B. Singlet state oxygen is capable to perform a direct insertion in the activated benzylic C-H bond of PS, 29 leading to IX. Also, the decomposition of the high energy peroxy intermediates can lead to reactive oxygen species (ROS), including hydroxyl radical and superoxide anion, which are highly oxidative and potent hydrogen atom Then a similar β-scission can occur leading to VI and VII, following then the same pathway as in Scheme 8, A.…”