Construction of Bisindolines via Oxidative Coupling Cyclization

Mechanistic duality of indolyl 1,3-heteroatom transposition

A novel mechanistic duality has been revealed from the indolyl 1,3-heteroatom transposition (IHT) of N-hydroxyindole derivatives. A series of in-depth mechanistic investigations suggests that two separate mechanisms are operating simultaneously. Moreover, the relative contribution of each mechanistic pathway, the energy barrier for each pathway, and the identity of the primary pathway were shown to be the functions of the electronic properties of the substrate system. Based on the mechanistic understanding obtained, a mechanism-driven strategy for the general and efficient introduction of a heteroatom at the 3-position of indole has been developed. The reaction developed exhibits a broad substrate scope to provide the products in various forms of the functionalised indole. Moreover, the method is applicable to the introduction of both oxygen- and nitrogen-based functional groups.

Synthesis of 3,3′-bisindoles via demethylenation

This work provides a mild demethylenation for the synthesis of 3,3′-bisindoles.

Direct C-H Functionalization of Tetrahydro-γ-Carbolines at α-Position

The direct C-H functionalization of tetrahydro-γ-carbolines (THγCs) at α-position has been presented. This mild and simple strategy allows coupling of THγCs with various anilines and indoles with satisfactory to excellent...

Aerobic Copper-Catalyzed Intramolecular Cascade Oxidative Isomerization/[4+4] Cyclization of 2,2'-Disubstituted Stilbenes

An aerobic copper-catalyzed cascade oxidative isomerization/[4+4] cyclization of 2,2'-disubstituted stilbenes is described. Under the mild CuCl/DBED/air catalytic system, various 5,10-heteroatom-containing tetrahydroindeno[2,1-a]indenes were efficiently prepared through the difunctionalizations of alkenes in a highly atom economic manner. Mechanistic investigations suggested the bicyclic product was likely formed through a sequence of rapid single-electron oxidation/[4+4] cyclization from 2,2'-disubstituted stilbene. The antarafacial manner of the thermally allowed [4+4] cyclization was further proven by series of control experiments and density functional theory calculations. Our findings provide an important addition to the aerobic copper-catalyzed oxidative cyclization.

Synthesis and Pharmacological Evaluation of Tetrahydro-γ-carboline Derivatives as Potent Anti-inflammatory Agents Targeting Cyclic GMP-AMP Synthase

The activation of cyclic GMP-AMP synthase (cGAS) by double-stranded DNA is implicated in the pathogenesis of many hyperinflammatory and autoimmune diseases, and the cGAS-targeting small molecule has emerged as a novel therapeutic strategy for treating these diseases. However, the currently reported cGAS inhibitors are far beyond maturity, barely demonstrating in vivo efficacy. Inspired by the structural novelty of compound 5 (G140), we conducted a structural optimization on both its side chain and the central tricyclic core, leading to several subseries of compounds, including those unexpectedly cyclized complex ones. Compound 25 bearing an N-glycylglycinoyl side chain was identified as the most potent one with cellular IC₅₀ values of 1.38 and 11.4 μM for h- and m-cGAS, respectively. Mechanistic studies confirmed its direct targeting of cGAS. Further, compound 25 showed superior in vivo anti-inflammatory effects in the lipopolysaccharide-induced mouse model. The encouraging result of compound 25 provides solid evidence for further pursuit of cGAS-targeting inhibitors as a new anti-inflammatory treatment.