A new dehydrogenative [4+1] annulation between para-quinone methides (p-QMs) and iodonium ylides for the synthesis of 2,3-dihydrobenzofurans

Yan-Jie Xiong, Shao-Qing Shi, Wen-Juan Hao,* Shu-Jiang Tu,* Bo Jiang*

A new dehydrogenative [4+1] annulation of para-quinone methides (p-QMs) with acyclic and cyclic phenyl iodonium ylides has been established, delivering a variety of functionalized 2,3-dihydrobenzofurans with the retention of quinone methide unit in generally good yields. The reaction pathway involves 1,6-nucleophilic addition, nucleophilic substitution and oxidation under mild metal-free and convenient conditions, and provides a practical access to construct benzofuran frameworks.

Org. Chem. Front. 2018, 5, 3483-3487; DOI: 10.1039/C8QO00950C