Silver‐Catalyzed Cross Dehydrogenative Coupling between Heteroarenes and Cyclic Ethers under Mild Conditions

Ag-Catalyzed cross-dehydrogenative-coupling for the synthesis of 1,4-dioxan-2-yl substituted quinazoline hybrids in an aqueous medium

We herein developed an effective approach for the construction of 2- or 4-(1,4-dioxan-2-yl) substituted quinazolines under mild conditions. A silver-K2S2O8 catalyzed direct CDC reaction between quinazolines and 1,4-dioxane for the synthesis of a series of 2- or 4-(1,4-dioxan-2-yl) substituted quinazoline hybrids is reported. The reaction proceeded well in water under mild conditions and showed a broad substrate scope and good functional group compatibility.

Copper-Catalyzed Synthesis of N-Fused Quinolines via C(sp3)-H Activation-Radical Addition-Cyclization Cascade

A novel copper-catalyzed cyclization reaction for the synthesis of pyrazolo[1,5-a]quinoline, triazolo[1,5-a]quinoline, and pyrrolo[1,2-a]quinoline derivatives is described. The process is initiated by di-tert-butyl peroxide-mediated C(sp3)-H activation to generate the α-functionalized radical, which supervenes a cascade radical addition/cyclization sequence to access the N-fused quinolines in good yields with broad functional group tolerance.

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp3)-H to construct C-C bonds

Ether derivatives are widespread as essential building blocks in various drugs, natural products, agrochemicals, and materials. Modern economy requires developing green strategies with improved efficiency and reduction of waste. Due to its atom and step-economy, the cross-dehydrogenative coupling (CDC) reaction has become a major strategy for ether functionalization. This review covers C-H/C-H cross-coupling reactions of ether derivatives with various C-H bond substrates via non-noble metal catalysts (Fe, Cu, Co, Mn, Ni, Zn, Y, Sc, In, Ag). We discuss advances achieved in these CDC reactions and hope to attract interest in developing novel methodologies in this field of organic chemistry.

Rapid construction of γ-lactam containing 3,3-disubstituted oxindoles via a silver-catalyzed cascade radical bicyclization reaction

An efficient cascade bicyclization strategy for the construction of γ-lactam containing 3,3-disubstituted oxindole derivatives is described, which enables the sequential assembly of both unactivated and activated double bonds in one pot.

Direct, Site-Selective and Redox-Neutral α-C-H Bond Functionalization of Tetrahydrofurans via Quantum Dots Photocatalysis

As one of the most ubiquitous bulk reagents available, the intrinsic chemical inertness of tetrahydrofuran (THF) makes direct and site-selective C(sp³ )-H bond activation difficult, especially under redox neutral condition. Here, we demonstrate that semiconductor quantum dots (QDs) can activate α-C-H bond of THF via forming QDs/THF conjugates. Under visible light irradiation, the resultant alkoxyalkyl radical directly engages in radical cross-coupling with α-amino radical from amino C-H bonds or radical addition with alkene or phenylacetylene, respectively. In contrast to stoichiometric oxidant or hydrogen atom transfer reagents required in previous studies, the scalable benchtop approach can execute α-C-H bond activation of THF only by a QD photocatalyst under redox-neutral condition, thus providing a broad of value added chemicals starting from bulk THFs reagent.