Ruthenium(II)-Catalyzed C–H Activation of Chromones with Maleimides to Synthesize Succinimide/Maleimide-Containing Chromones
Yan Zhou, Liang Hong, Yaoguang Sheng, Shaoli Wang, Yi Gao, Lingling Zhan, Zhilong Zheng, Mengjie Yang, Guang Liang, Jianmin Zhou, Jun Deng, Zengqiang Song
Abstract
An efficient route for the coupling of maleimides with chromones at the C5-position has been developed under Ru(II) catalysis. It could provide 1,4-addition products and oxidative Heck-type products by switching additives. Benzoic acid led to the formation of 1,4-addition products under solvent-free conditions, and silver acetate was promoted to the generation of oxidative Heck-type products. Various maleimides and chromones were suitable for this transformation, affording the desired products with good to excellent yields in a short reaction time. To understand the mechanism of this reaction, deuteration studies and control experiments have been performed.