Photocatalyst‐free, Visible Light‐mediated Paternò‐Büchi Reaction Between Dicarbonyl Compounds and Olefines

Abstract

The communication describes a general Paternò‐Büchi reaction under mild conditions, which is featured with visible light‐mediation, catalyst‐free and a broad range of substrates comparing with other strategies. Having overcome the synthetic limitations the PB reaction faces, this practical protocol can be employed to prepare a variety of multisubstituted oxetanes that often appear serving as important scaffolds in natural products and drugs. The common white light, the sole driving force in this case, can directly excite the carbonyl compounds to reach its triplet state, which then attacks an alkenes to generate a diradical intermediate, resulting in the oxetanes in high diastereoselectivity.

Visible photons as ideal reagents for the activation of coloured organic compounds

“…The reaction was optimized under continuous flow conditions and the products were obtained with similar satisfactory selectivity and yield. 93 Analogously, visible-light mediated Paternò–Büchi reactions on simple olefins have been performed by using anthraquinones 94 or α-ketoesters 95 as carbonyl donors.…”

Navigating Visible‐Light‐Triggered (aza and thia) Paternò‐Büchi Reactions for the Synthesis of Heterocycles

“…[16] Substrates expansion results show that acyclic olefns require longer reaction time than cyclic olefins, and there are In 2022, Zhou and co-workers reported a general Paternò-Büchi reaction between carbonyl compound and alkenes via white light irradiation (Scheme 7). [17] Through the strategy, a variety of functionalized oxetanes were produced from middle to excellent yields, and in high diastereoselectivity. Based on the mechanistic studies, the authors proposed the diradical pathway operated via direct sensitization of the activated carbonyl substrate.…”

Photocatalyst‐ and Transition‐Metal‐Free Light‐Induced Formation of Carbon‐Chalcogen Bonds

“…[46] For instance, Dell'Amico and co-workers reported a visible lightpromoted Paternò-Büchi reaction for constructing oxetoindolinic polycycles from indole and aromatic ketones. [47] Similarly, the Zhu group [48] utilized dicarbonyl compounds such as ketoesters, aromatic diketones, benzoyl cyanide, and aliphatic diketones, while the Su group [49] recently reported the use of Scheme 6. Catalyst-free sunlight-induced autoxidation of aldehydes to carboxylic acids.…”

“…For instance, Dell′Amico and co‐workers reported a visible light‐promoted Paternò‐Büchi reaction for constructing oxetoindolinic polycycles from indole and aromatic ketones [47] . Similarly, the Zhu group [48] utilized dicarbonyl compounds such as ketoesters, aromatic diketones, benzoyl cyanide, and aliphatic diketones, while the Su group [49] recently reported the use of anthraquinones as a carbonyl source for the synthesis of respective oxetane derivatives. Coote and co‐workers demonstrated the synthesis of spirocyclic oxetanes via Paternò‐Büchi reactions between cyclic ketones and maleic acid derivatives [50] .…”