Yuanqiong Huang

Design, synthesis, anti-TMV, fungicidal, and insecticidal activity evaluation of 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid derivatives based on virus inhibitors of plant sources.

By drawing the creation ideas of botanical pesticides, a series of tetrahydro-β-carboline-3-carboxylic acid derivatives were designed and synthesized, and first evaluated for their anti-TMV, fungicidal and insecticidal activities. Most of these derivatives exhibited good antiviral activity against TMV both in vitro and in vivo. Especially, the activities of compounds 8 and 15 in vivo were higher than that of ribavirin. The compound 8 exhibited more than 70% fungicidal activities against Cercospora arachidicola Hori, Alternaria solani, Bipolaris maydis, and Rhizoctonia solani at 50mg/kg, compounds 16 and 20 exhibited more than 60% insecticidal activities against Mythimna separate and Ostrinia nubilalis.

Design, Synthesis, and Antiviral, Fungicidal, and Insecticidal Activities of Tetrahydro-β-carboline-3-carbohydrazide Derivatives

According to our previous research on the antiviral activity of β-carboline and tetrahydro-β-carboline derivatives, using (1S,3S)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carbohydrazide (1) as a lead compound, series of novel tetrahydro-β-carboline derivatives containing acylhydrazone moiety were designed, synthesized, and first evaluated for their biological activities. Most of these compounds exhibited excellent antiviral activity both in vitro and in vivo. The in vivo inactivation, curative, and protection activities of compounds 8, 9, 12, 16, 28, 29, and 30 were much higher than that of ribavirin (37.6%, 39.4%, and 37.9% at 500 μg/mL) and the lead compound (40.0%, 42.3%, and 39.6% at 500 μg/mL). Especially, the in vitro and in vivo activities of compound 16 (36.9%, 33.6%, 30.2%, and 35.8%) at 100 μg/mL, which were very close to that of ribavirin (40.0% for in vitro activity) at 500 μg/mL. Compounds 9 and 29 were chosen for the field trials of antiviral efficacy against TMV (tobacco mosaic virus); the results exhibited that both compounds, especially compound 29, showed better activities than control plant virus inhibitors. At the same time, the fungicidal results showed that compounds 6, 9, and 11 exhibited good fungicidal activities against 14 kinds of phytopathogens. Additionally, compounds 3 and 23 exhibited moderate insecticidal activity against the four tested species of insects.

C ring may be dispensable for β-carboline: Design, synthesis, and bioactivities evaluation of tryptophan analog derivatives based on the biosynthesis of β-carboline alkaloids.

According to our previous work and the latest research on the biosynthesis of β-carboline, and using the reverse thinking strategy, tryptophan, the biosynthesis precursor of β-carboline alkaloids, and their derivatives were synthesized, and their biological activities and structure-activity relationships were studied. This bioassay showed that these compounds exhibited good inhibitory activities against tobacco mosaic virus (TMV); especially (S)-2-amino-3-(1H-indol-3-yl)-N-octylpropanamide (4) (63.3±2.1%, 67.1±1.9%, 68.7±1.3%, and 64.5±3.1%, 500μg/mL) exhibited the best antiviral activity both in vitro and in vivo. Compound 4 was chosen for the field trials and the acute oral toxicity test, the results showed that the compound exhibited good anti-TMV activity in the field and low acute oral toxicity. We also found that these compounds showed antifungal activities and insecticidal activities.

Regio- and chemoselective N-1 acylation of indoles: Pd-catalyzed domino cyclization to afford 1,2-fused tricyclic indole scaffolds.

A concise method for the synthesis of 1,2-fused tricyclic indole scaffolds by domino cyclization involving a Pd-catalyzed Sonogashira coupling, indole cyclization, regio- and chemoselective N-1 acylation, and 1,4-Michael addition is reported. This method provides straightforward access to tetrahydro[1,4]diazepino[1,2-a]indole and hexahydro[1,5]diazocino[1,2-a]indole scaffolds.

Copper-Catalyzed Aerobic Oxidative [2 + 3] Cyclization/Aromatization Cascade Reaction: Atom-Economical Access to Tetrasubstituted 4,5-Biscarbonyl Imidazoles

An atom-economical method for accessing tetrasubstituted 4,5-biscarbonylimidazoles by reaction between glycine derivatives and 5-alkoxyoxazoles is reported. The method, which involves a copper-catalyzed aerobic oxidative [2 + 3] cyclization/aromatization cascade process, starts from readily available and inexpensive materials, uses molecular oxygen as a co-oxidant, and has a broad substrate scope.

Synthesis of Structurally Diverse 2,3-Fused Indoles via Microwave-Assisted AgSbF6-Catalysed Intramolecular Difunctionalization of o-Alkynylanilines.

2,3-Fused indoles are found in numerous natural products and drug molecules. Although several elegant methods for the synthesis of this structural motif have been reported, long reaction times and harsh conditions are sometimes required, and the yields tend to be low. Herein, we report a microwave method for straightforward access to various types of 2,3-fused indoles via AgSbF6-catalysed intramolecular difunctionalization of o-alkynylanilines. AgSbF6 played a role in both the hydroamination step and the imine-formation step. This method, which exhibited excellent chemoselectivity (no ring-fused 1,2-dihydroquinolines were formed), was used for formal syntheses of the natural products conolidine and ervaticine and the antihistamine drug latrepirdine.

Design, Synthesis, and Biological Activity of β-Carboline Analogues Containing Hydantoin, Thiohydantoin, and Urea Moieties

A series of novel β-carboline derivatives was designed by combining the anti-tobacco mosaic virus (TMV) lead compound tetrahydro-β-carboline ester with the hydantoin, thiohydantoin, and urea motifs. These derivatives were synthesized from tetrahydro-β-carboline ester via a structural diversity-oriented synthesis in one step, and their biological activities were evaluated. Most of the derivatives exhibited anti-TMV activity higher than that of commercial plant virucide ribavirin, such as compounds 2, 4, 5, 7, 9, 15, 16, 19, and 21. Compared with the lead compounds, some of these derivatives showed good insecticidal activity against Plutella xylostella and Culex pipiens pallens. At the same time, these derivatives also showed broad-spectrum fungicidal activity. The systematic study provides strong evidence that the hydantoin, thiohydantoin, and urea motifs of these molecules can improve and modulate the activities of the analogues of natural products.

Dehydrogenation of N-Heterocycles by Superoxide Ion Generated through Single-Electron Transfer

Nitrogen-containing heteroarene motifs are found in numerous pharmaceuticals, natural products, and synthetic materials. Although several elegant methods for synthesis of these compounds through dehydrogenation of the corresponding saturated heterocycles have been reported, some of the methods are hampered by long reaction times, harsh conditions, and the need for catalysts that are not readily available. This work reports a novel method for dehydrogenation of N-heterocycles. Specifically, O2.- generated in situ acts as the oxidant for N-heterocycle substrates that are susceptible to oxidation through a hydrogen atom transfer mechanism. This method provides a general, green route to N-heteroarenes.