Convergent Synthesis of 1,4-Dicarbonyl <i>Z</i>-Alkenes through Three-Component Coupling of Alkynes, α-Diazo Sulfonium Triflate, and Water
Xuyong Wang, Xuyong Wang, Wen‐Yan Tong, Bing Huang, Si Cao, Yunlong Li, Jingchao Jiao, Hang Huang, Yi Qiu, Shuanglin Qu, Xi Wang, Xi Wang
Abstract
We report a general protocol for the convergent synthesis of 1,4-dicarbonyl Z-alkenes form alkynes using α-diazo sulfonium triflate and water. The C═O, C═C, and C–H bonds are formed under mild conditions with a wide range of functional groups tolerated. The reaction exhibits excellent Z-selectivity and complete regioselectivity. The resulting 1,4-dicarbonyl Z-alkenes can smoothly undergo follow-up conversion to a variety of heteroaromatic scaffolds. Moreover, the reaction also provides a facile access to the corresponding deuterated Z-alkenes and deuterated heteroarenes with a high level of deuterium incorporation (90–97% D-inc.) by directly using D2O, thus rendering the method highly valuable. The comprehensive mechanistic studies indicate that a free carbyne radical intermediate is formed via the photocatalytic single electron transfer process, and KH2PO4 plays a crucial role in significant improvements on yield and selectivity based on density-functional theory calculations, providing a new direction for radical coupling reactions of diazo compounds.