Dual C(sp3)-H Functionalization of Cyclic Ethers via Singlet Oxygen-Mediated Ring Opening and Ring Closing
Xu Yuan1, Xianglin Yu1, Kun He1
1Key Laboratory of Medicinal for Natural Resource, Ministry of Education and Yunnan Province, School of Chemical Science and Technology, Yunnan University, Kunming 650091, China.
Abstract:
A metal-free dual C(sp3)-H bond functionalization of saturated cyclic ethers via photooxidative singlet oxygen-mediated ring opening and ring closing has been developed, providing a method for generating hydrobenzofurans/pyrans/dioxins. Mechanistic studies have confirmed that ring-opening intermediates were effectively generated by singlet oxygen-mediated C(sp3)-H activation and efficiently reacted with aldehydes and activated methylene compounds to form a wide array of products with high diastereoselectivities (up to >95:5 dr). This study is a rare example of α,β-dual C(sp3)-H bond functionalization of ethers.
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