Solid-phase combinatorial synthesis of benzothiazole and 2,3-dihydro-[1,5]-benzothiazepine derivatives

Harnessing high potential benzothiazole chalcones against dengue virus NS5 protein: A multi-faceted theoretical study through molecular docking, ADME, and DFT

Chalcones bearing tetralone, indanone and benzothiazole cores were synthesized successfully using a general Claisen-Schmidt condensation protocol. The prepared compounds were purified and structurally analyzed by 1H, 13C NMR, and FT-IR techniques. A multi-faceted theoretical approach, combining Density Functional Theory (DFT), molecular docking, and ADME predictions, was employed to evaluate their therapeutic potential. DFT calculations at the B3LYP/def2-TZVP level revealed key electronic properties, with TD3 compound demonstrating the highest chemical reactivity. Molecular Electrostatic Potential (MEP) and Reduced Density Gradient (RDG) analyses provided insights into the compounds' non-covalent interactions and charge distributions. Molecular docking studies against the NS5 protein (PDB: 6KR2) showed superior binding affinities for all three compounds compared to the control ligand SAH, with TD3 exhibiting the lowest binding energy (-8.41 kcal/mol) and theoretical inhibition constant (689.31 nM). ADME predictions indicated favorable drug-like properties with concerns regarding aqueous solubility and potential P-glycoprotein interactions. Toxicity evaluations highlighted challenges, particularly in hepatotoxicity and carcinogenicity. The study identified TD3 as a promising lead compound for Dengue Virus NS5 inhibition, while also emphasizing the need for targeted modifications to address toxicity concerns. This research not only contributes to anti-dengue drug discovery efforts but also provides a robust methodological framework for the theoretical evaluation of similar small compounds in future investigations.

Synthesis, anti-inflammatory and analgesic evaluation of thiazole/oxazole substituted benzothiazole derivatives

Non-Steroidal biologically active heterocyclic compounds 4-(2-(4-chlorophenyl) benzo[d]thiazol-3(2H)-yl)-N-((3-substituted-2-hydrobenzo[d]thiazol-2-yl)methylene) thiazol-2-amine (3a-3d), 4-(2-(4-chlorophenyl)benzo[d]thiazol-3(2H)-yl)-N-((3-substituted - 2-hydrobenzo [d]thiazol-2-yl)methylene)oxazol-2-amine (3a'-3d'), (Z)-N'-(4-(2-(4-chlorophenyl)benzo[d]thiazol-3(2H)-yl)thiaol-2-yl)-N-(4-substituted phenylimino)-3-substituted-2-hydrobenzo[d]thiazole-2-carboxamidine (4a-4 h) and (Z)-N'-(4-(2-(4-chlorophenyl)benzo[d]thiazol-3(2H)-yl)oxazol-2-yl)-N-(4-substituted phenylimino) - 3-substituted-2-hydrobenzo[d]thiazole-2-carboxamidine (4a'-4h') were synthesized starting from 2-chloro-1-(2-(4-chlorophenyl)benzo[d]thiazol-3(2H)-yl) ethanone (1). The structure configuration of newly synthesized compounds has been determined by elemental analysis and various spectroscopic (IR, ¹HNMR and GCMS) techniques. These compounds were tested for their anti-inflammation, analgesic, ulcerogenic, acute toxicity and free radical scavenging action and compared with reference drugs in albino rats. Compound 4-(2-(4-chlorophenyl)benzo[d]thiazol-3(2H)-yl)-N-((3-substituted-2-hydrobenzo [d]thiazol-2-yl)methylene)thiazol-2-amine (3c) was the most active compound than reference drug at a dose of 50 mg/kg p.o.

A convenient route to 2-substituted benzothiazole-6-carboxylic acids using nitrobenzene as oxidant

Various substituted benzothiazole-6-carboxylic acids (4a–i) have been prepared by the condensation of 4-amino-3-mercaptobenzoic acid and aldehydes in nitrobenzene as oxidant. Compound 4i was found to be a good candidate as an inhibitor of β-hematin formation in vitro.

Functionalization of 3-chloroformylcoumarin to coumarin Schiff bases using reusable catalyst: an approach to molecular docking and biological studies

Recently, heterogeneous catalysts have been explored eximiously in the synthesis of heterocyclic compounds. Therefore, here we used solid-supported heterogeneous silica sulfuric acid as a catalyst for the synthesis of Schiff's base of 3-chloroformylcoumarin in view of simplified procedure, reusability and acceptable efficiency, which are required in organic synthesis. An efficient and facile methodology is preferred for synthesis of a class of chromeno-3-substituted derivatives (1a-1l) with good yields. The molecular docking results showed excellent binding interactions with the Mycobacterium tuberculosis InhA-D148G mutant (PDB: 4DQU). The same biomolecules were screened for their in vitro anti-tubercular activity against the M.tb H37Rv strain and antimicrobial studies. Physico-chemistry, toxicity prediction with IC50 value and bioactivity score were also calculated for title compounds. Most active compounds were further tested for cytotoxicity studies and exhibited low-level cytotoxicity against Vero cells. The suggested conjugates are promising lead compounds for the subsequent investigation in search of new anti-tubercular agents. All the conjugates were obtained within the range and followed the Lipinski rule of 5, indicating more 'drug-like' nature.

Recent advances in the synthesis of 2-substituted benzothiazoles: a review

Recent advances in various synthetic protocols of 2-substituted benzothiazole derivatives.

Dimethyl 3-acetyl-3-(1,3-benzothia-zol-2-yl)penta-nedioate

The title compound, C₁₆H₁₇NO₅S, was one of two condensation products from the reaction of 1-(1,3-benzothia­zol-2-yl)propan-2-one with methyl chloro­acetate. The non-H atoms in each of the four substituent groups on the central quaternary C atom are virtually coplanar. The maximum deviations from the least-squares planes are 0.015 (2) and 0.020 (2) Å for the methyl C atoms in the methyl acetate substituents and 0.033 (1) Å for the linked C atom of the benzothia­zole substituent. The S, C and N atoms in the thia­zole ring of the benzothia­zole substituent lie −0.037 (2), 0.046 (2) and −0.028 (2) Å, respectively, from the mean plane defined by the benzene ring atoms.

Synthesis and electronic absorption and fluorescence of 2-arylbenzothiazole derivatives

A series of new 2-arylbenzothiazoles have been prepared in high yields by Jacobson's cyclization condensation of 2-aminobenzenethiol with benzoyl chloride or benzaldehyde derivatives under three different routes. These compounds have been fully characterized by EA, IR, NMR and MS. The electronic absorption and fluorescence of these compounds have been systematically investigated for the first time. The relationships between their photophysical properties and structures have been discussed. The alteration of absorption and emission wavelengths can be elucidated by Hammett's substituent constants.

Syntheses and DNA-binding studies of a series of unsymmetrical cyanine dyes: structural influence on the degree of minor groove binding to natural DNA

Twelve crescent-shaped unsymmetrical dyes have been synthesized and their interactions with DNA have been investigated by spectroscopic methods. A new facile synthetic route to this type of cyanine dyes has been developed, involving the preparation of 6-substituted 2-thiomethyl-benzothiazoles in good yields. The new dyes are analogues to the minor groove binding unsymmetrical cyanine dye, BEBO, recently reported by us. In this dye, the structure of the known intercalating cyanine dye BO was extended with a 6-methylbenzothiazole substituent. Herein we further investigate the role of the extending benzazole heterocycle, as well as of the pyridine or quinoline moiety of the cyanine chromophore, for the binding mode of these crescent-shaped dyes to calf thymus DNA. Flow LD and CD studies of the 12 dyes show that the extent of minor groove binding to mixed sequence DNA varies significantly between the dyes. We find that hydrophobicity and size are the crucial parameters for recognition of the minor groove. The relatively high fluorescence quantum yield of many of these cyanines bound to DNA, combined with their absorption at long wavelengths, may render them useful in biological applications. In particular, two of the benzoxazole containing dyes BOXTO and 2-BOXTO show a high degree of minor groove binding and quantum yields of 0.52 and 0.32, respectively, when bound to DNA.

The recent impact of solid-phase synthesis on medicinally relevant benzoannelated nitrogen heterocycles

Benzoannelated heterocycles such as benzodiazepines and indoles can be prepared efficiently through cyclization on solid supports, although no single approach is currently universal for the preparation of all benzoannelated N-heterocycle chemistries. In this review, a number of synthetic strategies for the generation of benzoannelated nitrogen heterocycles using resin-bound substrates have been described. Classical heterocycle forming reactions such as the Fischer indole, the Bischler-Napieralski tetrahydroisoquinoline, the Pictet-Spengler tetrahydro-beta-carboline, the Tsuge, the Nenitzescu and the Richter cinnoline reaction are presented. In addition, the Heck, Sonogashira, Wittig, Diels-Alder, and olefin metathesis reactions have been also used. Multicomponent reactions such as the Grieco three-component assembly have been exploited for the synthesis of heterocycles. Cyclative cleavage from the solid support is particularly suitable for the synthesis of heterocycles while particular emphasis has been focused on the synthesis of libraries and the use of combinatorial chemistry techniques. In addition, the most relevant pharmacological properties of benzoannelated nitrogen heterocycles are included.