Regioselective Cross-Couplings of Coumarins and Flavones with Ethers via C(sp³)–H Functionalization

Abstract

Coumarin and flavone derivatives are highly valuable molecules in drug discovery. Here, two new regioselective cross-dehydrogenation couplings of coumarins and flavones with different ethers via C(sp(3))-H functionalization processes were developed, generating new ether-substituted derivatives not previously reported. These reactions proceeded well via radical mechanisms and provided the corresponding products in good yields.

Direct oxidative C(sp3)─H/C(sp2)─H coupling reaction using recyclable Sr‐doped LaCoO3 perovskite catalyst

“…Similar to other oxidative coupling reactions, an oxidant was required for the C(sp 3 coupling reaction between 1,1-diphenylethylene and THF. We therefore tested a series of oxidants for this reaction, including both inorganic and organic oxidants (entries [16][17][18][19][20][21][22][23][24]. It was noted that the reaction was markedly controlled by the nature of the oxidant.…”

“…[14,15] Niu et al previously reported a FeCl 3 -catalyzed oxidative coupling transformation of coumarins to afford corresponding α-functionalized ethers. [16] Indeed, the field still remains to be fully explored.…”

Recent Advances of Oxidative Radical Cross‐Coupling Reactions: Direct α‐C(sp3)–H Bond Functionalization of Ethers and Alcohols

“…Many coumarin and flavone derivatives with various functional groups on their α‐ and β‐positions were obtained via C–H bond functionalization by transition metal catalysts . In 2015, Zhou and co‐workers reported a regioselective radical oxidative coupling of coumarins with different ethers via a radical addition process (Scheme ) . Moreover, this method also could be successfully applied to flavones.…”

Cross-dehydrogenative coupling of coumarins with Csp3–H bonds using an iron–organic framework as a productive heterogeneous catalyst

“…Niu et al previously performed the direct couplings of coumarins with cyclic ethers using a FeCl 3 catalyst. 11 Wang et al synthesized a variety of C-3 functionalized coumarins via the Cu(OAc) 2 catalyzed reaction with cyclic ethers and cycloalkanes. 12 Cao et al developed a novel approach for the direct Csp 2 -H radical triuoromethylation of coumarins in the presence of Mn(OAc) 3 .…”