Difluorination of Furonaphthoquinones

Photoinduced Metal-Free Radical Addition/Cyclization of 2-Cyanoaryl Acrylamides to Prepare gem-Difluorinated Naphthyridinone Scaffolds

Direct construction of gem-difluorinated heterocycles represents a long-standing challenge in organic chemistry. Herein, we developed a transition-metal-free photocatalytic radical addition/cyclization of BrCF2COR with 2-cyanoaryl acrylamides to give gem-difluorinated naphthyridinone scaffolds in moderate to good yields. Furthermore, some natural products were found to be suitable in the reaction system. The easily available substrates, mild reaction conditions, simple operation, and wide functionality tolerance show practical and environmental advantages in this method.

Research and Development of Natural Product Tanshinone I: Pharmacology, Total Synthesis, and Structure Modifications

Salvia miltiorrhiza (S. miltiorrhiza), which has been used for thousands of years to treat cardiovascular diseases, is a well-known Chinese medicinal plant. The fat-soluble tanshinones in S. miltiorrhiza are important biologically active ingredients including tanshinone I, tanshinone IIA, dihydrotanshinone, and cryptotanshinone. Tanshinone I, a natural diterpenoid quinone compound widely used in traditional Chinese medicine, has a wide range of biological effects including anti-cancer, antioxidant, neuroprotective, and anti-inflammatory activities. To further improve its potency, water solubility, and bioavailability, tanshinone I can be used as a platform for drug discovery to generate high-quality drug candidates with unique targets and enhanced drug properties. Numerous derivatives of tanshinone I have been developed and have contributed to major advances in the identification of new drugs to treat human cancers and other diseases and in the study of related molecular mechanisms. This review focuses on the structural modification, total synthesis, and pharmacology of tanshinone I. We hope that this review will help understanding the research progress in this field and provide constructive suggestions for further research on tanshinone I.

Palladium-Catalyzed gem-Difluoroallylation Reaction between Aryltributyltin and Bromodifluoromethylated Alkenes

A robust Stille gem-difluoroallylation of arylstannanes with 3-bromo-3,3-difluoropropenes has been established. The catalyst was found to exert critical effect on the reaction chemoselectivity. By using Pd(OH)₂/C as the catalyst, a series of 3-(hetero)aryl/vinyl-3,3-difluoropropenes were obtained in high efficiency with α-substitution regioselectivity. The reaction has a broad substrate scope, and various substitution patterns were well tolerated in both substrates. Notably, the reaction can be easily extended to late-stage gem-difluoroallylation of many bioactive molecules with good chemoselectivity.

Selective electrophilic di- and mono-fluorinations for the synthesis of 4-difluoromethyl and 4-fluoromethyl quinazolin(thi)ones by Selectfluor-triggered multi-component reaction

A simple and efficient domino protocol for the selective synthesis of 4-difluoromethyl and 4-fluoromethyl quinazolin(thi)ones was established from readily available 2-aminoacetophenones and iso(thio)cyanates mediated by Selectfluor. The reaction outcomes are...

Tanshinone IIA: Pharmacology, total synthesis, and progress in structure-modifications

Tanshinone IIA, a major bioactive constituent of Danshen, a Chinese herbal medicine, has gained extensive exploration owing to its unique structural features and multiple promising biological activities. This review focuses on the pharmacology, total synthesis, and structural modifications of tanshinone IIA. We hope this review will contribute to a better understanding of the progress in the field and provide constructive suggestions for further study of tanshinone IIA.

Thirteen undescribed diterpenoid quinones derived from the rhizomes of Salvia miltiorrhiza and their anti-tumor activities

Thirteen undescribed diterpenoid quinones were isolated from the dried roots of Salvia miltiorrhiza. Their structures were determined by extensive analysis, including NMR, HRESIMS, and IR. Their absolute configurations were determined by X-ray diffraction, calculated and experimental circular dichroism spectroscopy, and optical rotation. In the evaluation of bioactivities, salviadionether obviously inhibited the proliferation of HCT-116 cells. R-(+)-salmiltiorin E and R-(+)-grandifolia D both showed inhibitory activities on a variety of tumor cells. Salvianone ester A showed strong cytotoxicity to tumor-repopulating cells (TRCs) with an IC₅₀ value of 2.19 μM.

Tanshinones and their Derivatives: Heterocyclic Ring-Fused Diterpenes of Biological Interest

The available scientific literature regarding tanshinones is very abundant, and after its review, it is noticeable that most of the articles focus on the properties of tanshinone I, cryptotanshinone, tanshinone IIA, sodium tanshinone IIA sulfonate and the dried root extract of Salvia miltiorrhiza (Tan- Shen). However, although these products have demonstrated important biological properties in both in vitro and in vivo models, their poor solubility and bioavailability have limited their clinical applications. For these reasons, many studies have focused on the search for new pharmaceutical formulations for tanshinones, as well as the synthesis of new derivatives that improve their biological properties. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2015) on tanshinones in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we offer an update on the last five years of new research on these quinones, focusing on their synthesis, biological activity on noncommunicable diseases and drug delivery systems, to support future research on its clinical applications.

Biomimetic synthesis of the natural product salviadione and its hybrids: discovery of tissue-specific anti-inflammatory agents for acute lung injury

Biomimetic synthesis of the natural product salviadione and its hybrids was achieved leading to tissue-specific anti-inflammatory agents for acute lung injury.

Acute lung injury (ALI) is an inflammatory disease with no effective pharmacological treatment. The therapeutic potential of the anti-inflammatory natural product tanshinone IIA (2) for ALI is seriously impaired by its poor pharmacokinetic (PK) properties. Inspired by the unique benzo[def]carbazole-3,5-dione (BCD) core of the natural product salviadione (5), a series of furan-fused BCD hybrids of 5 with 2 was rationally designed with the aim to improve both PK properties and the anti-inflammatory activity. A biomimetic synthetic approach featuring one-pot tandem N-heterocyclization was first developed for convenient assembly of salviadione (56% overall yield over 2 steps) and the designed hybrids (35–85% yields in one step). Compared to 2, most of the resulting compounds exhibited a markedly enhanced inhibitory effect against LPS-induced release of pro-inflammatory cytokines in macrophages. Particularly, compound 15a not only possessed the most potent activity in vitro, but also exhibited significantly improved metabolic stability (4- to 7-fold enhancement), pharmacokinetic properties (T_1/2 = 4.05 h; F = 30.2%), and preferable lung tissue distribution (11- to 300-fold selectivity). An in vivo study in mice showed that pretreatment with 15a at 5 mg kg^–1 distinctly attenuated LPS-induced ALI via lung tissue-specific anti-inflammatory actions, indicating that the furan-fused BCD core presents a unique chemotype with promising therapeutic potential for ALI.

Discovery of Indoleamine 2,3-Dioxygenase 1 (IDO-1) Inhibitors Based on Ortho-Naphthaquinone-Containing Natural Product

There is great interest in developing small molecules agents capable of reversing tumor immune escape to restore the body’s immune system. As an immunosuppressive enzyme, indoleamine 2,3-dioxygenase 1 (IDO-1) is considered a promising target for oncology immunotherapy. Currently, none of IDO-1 inhibitors have been launched for clinical practice yet. Thus, the discovery of new IDO-1 inhibitors is still in great demand. Herein, a series of diverse ortho-naphthaquinone containing natural product derivatives were synthesized as novel IDO-1 inhibitors. Among them, 1-ene-3-ketone-17-hydroxyl derivative 12 exhibited significantly improved enzymatic and cellular inhibitory activity against IDO-1 when compared to initial lead compounds. Besides, the molecular docking study disclosed that the two most potent compounds 11 and 12 have more interactions within the binding pocket of IDO-1 via hydrogen-bonding, which may account for their higher IDO-1 inhibitory activity.

Total synthesis of (±)-tanshinol B, tanshinone I, and (±)-tanshindiol B and C

A concise and efficient approach was established for the divergent total synthesis of (±)-tanshinol B, (±)-tanshindiol B, (±)-tanshindiol C, and tanshinone I in 17–50% overall yield over 3–6 steps.