Visible-Light-Promoted Aerobic Oxyphosphorylation of α-Diazoesters with H-Phosphine Oxides

Abstract

A visible-light-promoted aerobic oxyphosphorylation of α-diazoesters and H-phosphine oxides has been developed. Using air as the oxygen source, the reaction proceeded smoothly at room temperature under blue-light irradiation. The α-diazoesters, molecular oxygen, and H-phosphine oxides are conveniently incorporated into a C–O–P­(O) unit in one step. The preliminary mechanistic studies indicated that a light-triggered radical process is involved. The developed strategy shows the unrevealed reactivity of diazo compounds with H-phosphine oxides and has potential value in synthetic applications.

Visible-Light-Initiated Multicomponent Reactions of α-Diazoesters to Access Organophosphorus Compounds

“…Finally, intermediate 13a underwent the intramolecular hydrogen transfer producing the desired product 4a . The coupling of carbon radical 8a with phosphoryloxy radical 14a would produce the product 5a , which is consistent with the result of a previous report …”

“…On the basis of the above experiments and referring to previous reports, − a possible reaction mechanism was proposed as shown in Scheme . First, the photoexcitation of methyl phenyldiazoacetate 1a formed an excited state 1a* , which underwent denitrogenation to give free carbene intermediate 6a under visible-light irradiation.…”

“…Subsequently, free carbene intermediate 6a was quickly attacked by THF to afford oxonium ylide intermediate 7a . On the other hand, the hydrogen atom abstraction of carbene intermediate 6a from diphenylphosphine oxide 2a would also lead to the formation of carbon radical 8a and phosphinoyl radical 9a . , The interaction of phosphinoyl radical 9a with dioxygen in air generates a peroxy radical intermediate 10a , which would abstract a hydrogen atom from 2a leading to phosphinoyl radical 9a and phosphoryl hydroperoxide 11a . Phosphoryl hydroperoxide 11a was further reduced by 2a to give diphenylphosphinic acid 12a .…”

“…As clean and sustainable energy, visible light has been widely applied to promote various types of organic reactions. , In particular, visible-light-induced carbene transfer reactions of diazo compounds have been developed as an attractive and efficient protocol for the rapid assemble of the densely functionalized molecules via free carbene intermediates due to their mild and metal-free advantages. , In 2022, Yang and Zhou presented a visible-light-mediated aerobic oxyphosphorylation of α-diazoesters and H-phosphine oxides to access α-phosphoryloxy carbonyl compounds (Scheme d) . Since Szabó and Koenigs independently reported metal-catalyzed and photochemical ring opening of cyclic ethers with diazo compounds and N -fluorobenzenesulfonimide, multicomponent reactions of aryldiazoacetates, cyclic ethers, and nucleophiles have attracted great attention of chemists in synthetic community .…”

“…15,16 In 2022, Yang and Zhou presented a visible-light-mediated aerobic oxyphosphorylation of α-diazoesters and H-phosphine oxides to access αphosphoryloxy carbonyl compounds (Scheme 1d). 17 Since Szabó1 8 and Koenigs 19 independently reported metal-catalyzed and photochemical ring opening of cyclic ethers with diazo compounds and N-fluorobenzenesulfonimide, multicomponent reactions of aryldiazoacetates, cyclic ethers, and nucleophiles have attracted great attention of chemists in synthetic community. 20 Very recently, our group also described visiblelight-promoted strategy for the preparation of S-alkyl phosphorothioates through base-mediated four-component reactions of α-diazoesters, elemental sulfur, cyclic ethers, and H-phosphonates.…”