C(sp3)–H Bond Functionalization of Benzo[c]oxepines via C–O bond Cleavage: Formal [3+3] Synthesis of Multisubstituted Chromans
journal contributionposted on 2018-02-19, 00:00 authored by Miao Wang, Bo-Cheng Tang, Jia-Chen Xiang, Yan Cheng, Zi-Xuan Wang, Jin-Tian Ma, Yan-Dong Wu, An-Xin Wu
An efficient base-promoted C(sp3)–H bond functionalization strategy for the synthesis of multisubstituted chromans from the formal [3+3] cycloaddition of benzo[c]oxepines and electron-rich phenols has been developed. The corresponding 4H-chromenes can be easily obtained in excellent yields by simple filtration from chromans. Preliminary mechanistic studies indicate that the C–O bond cleavage is the key step for the C(sp3)–H bond functionalization and that this reaction could have occurred through tandem C–O bond cleavage/Michael addition/annulation reactions.