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DBU-Mediated Reaction of 3-Chlorooxindole and 9-Xanthyl Fluorene for Synthesis of 3-Arylidene Oxindole
(2025-04-01)
Purahong, Nitchakan
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Teerawatananond, Thapong
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Chotsaeng, Nawasit
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Janthakit, Pattarapapa
;
Nalaoh, Phattananawee
This work reports a new route for the synthesis of 3-(9H-fluoren-9-ylidene)indolin-2-one derivatives via the reaction of 3-chlorooxindoles and O-ethyl S-(9H-fluoren-9-yl) carbonodithioates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The reactions readily proceeded at room temperature, enable a collection of 3-alkenyl oxindoles to be prepared within a short reaction time (15 minutes). The 3-alkenyl oxindoles can be easily converted to 3-fluorenyl oxindoles by NaBH<inf>4</inf> reduction.
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Electrochemically driven reductive cyclization of o-nitroanilines: synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles
(2025-03-31)
Saetan, Jutamart
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Purahong, Nitchakan
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La-Ongthong, Kannika
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Hassa, Nattawoot
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Chotsaeng, Nawasit
The electrochemical synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles from o-nitroanilines in an undivided cell under constant current conditions was developed. The electrosynthesis proceeded through a tandem process involving nitro reduction/C(sp<sup>3</sup>)-H amination/condensation. The method can accommodate a broad range of o-nitroanilines and results in the desired products in yields of up to 99%. A plausible reaction mechanism was proposed on the basis of controlled experiments and cyclic voltammetry (CV) analysis. The benefits of the developed method include one-pot synthesis, open-air conditions, gram-scale synthesis and no requirement for a strong reductant.
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Revisiting chloroplast genomic landscape and annotation towards comparative chloroplast genomes of Rhamnaceae
(2023-12-01)
Wanichthanarak, Kwanjeera
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Nookaew, Intawat
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Pasookhush, Phongthana
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Wongsurawat, Thidathip
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Jenjaroenpun, Piroon
Background: Massive parallel sequencing technologies have enabled the elucidation of plant phylogenetic relationships from chloroplast genomes at a high pace. These include members of the family Rhamnaceae. The current Rhamnaceae phylogenetic tree is from 13 out of 24 Rhamnaceae chloroplast genomes, and only one chloroplast genome of the genus Ventilago is available. Hence, the phylogenetic relationships in Rhamnaceae remain incomplete, and more representative species are needed. Results: The complete chloroplast genome of Ventilago harmandiana Pierre was outlined using a hybrid assembly of long- and short-read technologies. The accuracy and validity of the final genome were confirmed with PCR amplifications and investigation of coverage depth. Sanger sequencing was used to correct for differences in lengths and nucleotide bases between inverted repeats because of the homopolymers. The phylogenetic trees reconstructed using prevalent methods for phylogenetic inference were topologically similar. The clustering based on codon usage was congruent with the molecular phylogenetic tree. The groups of genera in each tribe were in accordance with tribal classification based on molecular markers. We resolved the phylogenetic relationships among six Hovenia species, three Rhamnus species, and two Ventilago species. Our reconstructed tree provides the most complete and reliable low-level taxonomy to date for the family Rhamnaceae. Similar to other higher plants, the RNA editing mostly resulted in converting serine to leucine. Besides, most genes were subjected to purifying selection. Annotation anomalies, including indel calling errors, unaligned open reading frames of the same gene, inconsistent prediction of intergenic regions, and misannotated genes, were identified in the published chloroplast genomes used in this study. These could be a result of the usual imperfections in computational tools, and/or existing errors in reference genomes. Importantly, these are points of concern with regards to utilizing published chloroplast genomes for comparative genomic analysis. Conclusions: In summary, we successfully demonstrated the use of comprehensive genomic data, including DNA and amino acid sequences, to build a reliable and high-resolution phylogenetic tree for the family Rhamnaceae. Additionally, our study indicates that the revision of genome annotation before comparative genomic analyses is necessary to prevent the propagation of errors and complications in downstream analysis and interpretation.
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DBU-Mediated Dimerization: Facile Access to 9,9′-Bifluorenylidenes and Isoindigos
(2023-11-14)
Purahong, Nitchakan
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Hongthong, Sakchai
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Chotsaeng, Nawasit
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Kuhakarn, Chutima
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Meesin, Jatuporn
The present work describes the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted self-dimerization of 9-chlorofluorenes and 3-chlorooxindoles for the preparation of the corresponding 9,9 -bifluorenylidene and isoindigo derivatives in moderate to good yields of 29 97%. The reactions proceed readily in a short reaction time under mild and metal-free conditions. Scale-up syntheses (5.0 mmol) of selected 9,9 -bifluorenylidene derivatives proceed in decent yields, highlighting the synthetic utility of the reported protocol.
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Sulfonylated Indeno[1,2-c]quinoline Derivatives as Potent EGFR Tyrosine Kinase Inhibitors
(2023-06-06)
Hengphasatporn, Kowit
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Aiebchun, Thitinan
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Mahalapbutr, Panupong
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Auepattanapong, Atima
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Khaikate, Onnicha
The epidermal growth factor receptor (EGFR) has been considered a potential target for lung cancer therapy due to its essential role in regulating the survival and proliferation of cancer cells. Although erlotinib, a potent EGFR tyrosine kinase (EGFR-TK) inhibitor, has been used as the first-line drug for lung cancer treatment, acquired drug resistance caused by the T790M secondary mutation of EGFR-TK inevitably develops after a median response duration of 9-13 months. Thus, the search for promising compounds to effectively target EGFR-TK has become an imperative necessity. In this study, the kinase inhibitory activities of a series of sulfonylated indeno[1,2-c]quinolines (SIQs) against EGFR-TK were experimentally and theoretically investigated. Among the 23 SIQ derivatives studied, eight compounds showed enhanced EGFR-TK inhibitory activity (IC<inf>50</inf> values of ca. 0.6-10.2 nM) compared to the known drug erlotinib (IC<inf>50</inf> of ∼20 nM). In a cell-based assay in human cancer cell lines with EGFR overexpression (A549 and A431 cells), the eight selected SIQs all showed more significant cytotoxicity against A431 than A549 cells, consistent with the higher EGFR expression in A431 cells. Molecular docking and FMO-RIMP2/PCM calculations revealed that SIQ17 occupies the ATP-binding site of EGFR-TK, where its sulfonyl group is mainly stabilized by C797, L718, and E762 residues. Triplicate 500 ns molecular dynamics (MD) simulations also confirmed the binding strength of SIQ17 in complex with EGFR. Overall, the potent SIQ compounds obtained in this work could be further optimized for developing novel anticancer drug candidates targeting EGFR-TK.
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Dimerization of 3-Chlorooxindoles Mediated by Potassium Ethylxanthate: Synthesis of Isoindigos
(2022-08-17)
Meesin, Jatuporn
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Chotsaeng, Nawasit
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Kuhakarn, Chutima
A novel dimerization of 3-chlorooxindoles promoted by potassium ethylxanthate to access isoindigo derivatives is described. The reactions proceeded readily at room temperature in short reaction times. A mechanistic study revealed that the 3-chlorooxindole is initially converted into O-ethyl S-(2-oxo-2,3-dihydro-1H-indol-3-yl) dithiocarbonate, which subsequently undergoes dimerization with elimination of arbon disulfide. In almost all cases, analytically pure isoindigos were isolated in moderate to good yields without a requirement for chromatographic purification.
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Synthesis of indolo- and benzothieno[3,2-c]quinolines via POCl3 mediated tandem cyclization of o-alkynylisocyanobenzenes derived from o-alkynyl-N-phenylformamides
(2022-08-01)
Uppalabat, Thikhamporn
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Tapdara, Anyawan
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Khaikate, Onnicha
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Worakul, Thanapat
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Surawatanawong, Panida
A synthesis of indolo[3,2-c]quinolines and benzothieno[3,2-c]quinolines has been developed employing o-alkynyl-N-phenylformamide derivatives as the substrates. The reaction proceeded via a tandem process involving POCl<inf>3</inf>-assisted intramolecular cyclization of the firstly formed o-alkynylisocyanobenzenes, leading to the desired products in moderate to high yields. Furthermore, the reaction is efficient on a gram-scale and the products were structurally modified by amination, Suzuzki-Miyaura reaction and Heck cross-coupling. Photophysical properties of several selected indolo[3,2-c]quinolines were studied by UV-Visible and fluorescence spectroscopy and rationalized using time-dependent DFT calculations.

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