The regiospecific synthesis of 5- and 7-monosubstituted and 5,6-disubstituted 2-arylbenzothiazoles

Synthesis and Docking Study of Some Bioactive N-(benzo[d]thiazol-2-yl)- 2-(4-((substituted)phenoxy)acetamide on Cyclo-oxygenase-2 Enzyme and In vivo Analgesic Activity Evaluation

Background::

The benzothiazole and its derivatives reported an extremely crucial duty in the progress of commercially important intermediary molecules, which are wanted for the manufacturing of various pharmacologically active agents.

Introduction::

As a necessary element of ongoing examination for the synthesis of new nonsteroidal anti-inflammatory agents (NSAIDs), a number of new benzothiazole derivatives were taken under consideration for the synthesis and were computationally studied along with their biological activity.

Methods::

Obtainable benzothiazole derivatives were synthesized by the condensing of 2-(4- aminophenoxy)-N-(benzo[d]thiazol-2-yl)acetamide with substituted acetophenones in ethanol in the presence of a catalytic amount of glacial acetic acid. The structures of newly synthesized compounds were characterized by IR, NMR spectroscopy and elemental analysis techniques. Several molecular properties of these derivatives were computed in order to estimate their drug like candidates. Molecular docking was performed to these synthesized derivatives with particular reference to cyclooxygenase-2 (COX-2) enzyme. The synthesized derivatives were screened for their biological activity, including analgesic and anti-inflammatory activity as COX-2 inhibitors.

Results and Discussion::

From all data, it established that among all target compounds, S-4 (N-(benzo[d]thiazol- 2-yl)-2-(4-((1-(3-nitrophenyl)ethylidene)amino)phenoxy)acetamide) displayed the highest antiinflammatory and analgesic effects.

Conclusion::

All these findings recommended that S-4 might be utilized as a promising new lead compound for Nonsteroidal anti-inflammatory drug (NSAIDs) development.

Synthesis and antileishmanial activity of fluorinated rhodacyanine analogues: The 'fluorine-walk' analysis

In a search for potent antileishmanial drug candidates, eighteen rhodacyanine analogues bearing fluorine or perfluoroalkyl substituents at various positions were synthesized. These compounds were tested for their inhibitory activities against Leishmania martiniquensis and L. orientalis. This 'fluorine-walk' analysis revealed that the introduction of fluorine atom at C-5, 6, 5', or 6' on the benzothiazole units led to significant enhancement of the activity, correlating with the less negative reduction potentials of the fluorinated analogues confirmed by the electrochemical study. On the other hand, CF₃ and OCF₃ groups were found to have detrimental effects, which agreed with the poor aqueous solubility predicted by the in silico ADMET analysis. In addition, some of the analogues including the difluorinated species showed exceptional potency against the promastigote and axenic amastigote stages (IC₅₀ = 40-85 nM), with the activities surpassing both amphotericin B and miltefosine.

A new synthesis and crystal structure of the ethyl 4,6-dibromobenzothiazol-2-ylcarbamate

The title compound was synthesised by the reaction of N-ethoxycarbonyl-N'-(2,4,6–tribromo-phenyl)thiourea with copper chloride in ethanol solution. Cyclisation of the ethoxycarbonylthiourea formed the ethyl 4,6-dibromo benzothiazol-2-ylcarbamate.

Recent advances in photocatalytic C–S/P–S bond formation via the generation of sulfur centered radicals and functionalization

In this review, we have focused on the recent advances in photocatalytic C–S/P–S bond formation via the generation of thioyl/sulfonyl radicals and further functionalization.

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

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

Chemistry of ring-substituted 4-(benzothiazol-2-yl)phenylnitrenium ions from antitumor 2-(4-aminophenyl)benzothiazoles

Ring-substituted derivatives of 2-(4-aminophenyl)benzothiazole, 1a, 1b-g, are under development as antitumor agents. One derivative, 1f, has reached phase 1 clinical trials as the prodrug 2f, Phortress (NSC 710305). These amines are activated by CYP450 1A1, apparently into hydroxylamines 8a-g that are likely metabolized into esters that ionize into nitrenium ions responsible for cellular damage. Previously we showed that 9a, the acetic acid ester of 8a, generates the long-lived (530 ns) nitrenium ion 11a by hydrolysis or photolysis in water. In this study, azide trapping shows that 9b-g generate 11b-g via rate-limiting N-O heterolysis. Ion lifetimes, estimated from azide/solvent selectivities, range from 250 to 1150 ns with identical lifetimes for 11a and 11f. Differences in biological activity of the amines are likely not due to differences in the chemistry of the cations but to differences in metabolic activation/deactivation of individual amines. Unlike the nitrenium ions, lifetimes of the esters are strongly dependent on the 3'-Me substituent. Esters containing 3'-Me (9b, 9f, 9g) have lifetimes of 5-10 s compared to 400-800 s for esters without 3'-Me (9a, 9c, 9d, 9e). This restricts 3'-Me esters to cells/tissues in which activation occurs, concentrating their effects in tumor cells if metabolism is restricted to those cells.

An efficient synthesis of 2-arylbenzothiazoles using silica sulfuric acid, oxalic acid and aluminum chloride hydrate as heterogeneous and homogeneous catalyst systems

A convenient method for the synthesis of 2-arylbenzothiazoles from condensation of aromatic/heteroaromatic aldehydes with 2-aminothiophenol has been developed using inexpensive, green and reusable solid acids – silica sulfuric acid (SSA), oxalic acid or AlCl3·6H2O as efficient catalysts. The reactions occurred under mild conditions to afford the corresponding 2-arylbenzothiazoles in good to excellent yields.

An inter-molecular dative B←N bond in 5-(4,4,5,5-tetra-methyl-1,3,2-dioxa-borolan-2-yl)-1,3-thia-zole

The title compound, C₉H₁₄BNO₂S, is in an unusual bend conformation and the B atom of one mol­ecule within the crystal forms an inter­molecular dative bond with the N atom of a neighbouring mol­ecule, an infrequent phenomenon in boronic derivative crystals.

Cerium (IV) ammonium nitrate (CAN) catalyzed one-pot synthesis of 2-arylbenzothiazoles

A one-pot synthesis of 2-arylbenzothiazoles from the reaction of 2-amino-thiophenol and aromatic aldehydes catalysed by cerium (IV) ammonium nitrate (CAN) is reported.

Synthesis and biological properties of benzothiazole, benzoxazole, and chromen-4-one analogues of the potent antitumor agent 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (PMX 610, NSC 721648)

New fluorinated 2-aryl-benzothiazoles, -benzoxazoles, and -chromen-4-ones have been synthesized and their activity against MCF-7 and MDA 468 breast cancer cell lines compared with the potent antitumor benzothiazole 5. Analogues such as 9a, b and 12a, d yielded submicromolar GI50 values in both cell lines; however, none of the new compounds approached 5 in terms of antitumor potency. For 5, binding to the aryl hydrocarbon receptor appeared to be necessary but not sufficient for growth inhibition.

Synthesis, antiproliferative and antifungal activities of some 2-(2,4-dihydroxyphenyl)-4H-3,1-benzothiazines

A new method for the synthesis of 4H-3,1-benzothiazine skeleton is described. The compounds were obtained by the reaction of sulfinylbis(2,4-dihydroxythiobenzoyl) with o-substituted anilines bearing an activated methylene group (-CH2OH, -CH2NR1R2), o-aminobenzanilides or 2-aminobenzophenones. The reaction proceeded through thiobenzanilide intermediates, which were converted to the 4H-3,1-benzothiazine fused ring by an endocyclization process. The compounds were tested for their antiproliferative properties against the cells of a human breast cancer T47D line. The activity of some compounds was comparable to that of cisplatin, studied as a control. A strong antifungal effect against the strains of moulds, yeasts and dermatophytes was also found.

Antitumor benzothiazoles. 26.(1) 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (GW 610, NSC 721648), a simple fluorinated 2-arylbenzothiazole, shows potent and selective inhibitory activity against lung, colon, and breast cancer cell lines

A series of new 2-phenylbenzothiazoles has been synthesized on the basis of the discovery of the potent and selective in vitro antitumor properties of 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (8n; GW 610, NSC 721648). Synthesis of analogues substituted in the benzothiazole ring was achieved via the reaction of o-aminothiophenol disulfides with substituted benzaldehydes under reducing conditions. Compounds were evaluated in vitro in four human cancer cell lines, and compound 8n was found to possess exquisitely potent antiproliferative activity (GI(50) < 0.1 nM for MCF-7 and MDA 468). Potent and selective activity was also observed in the NCI 60 human cancer cell line panel. Structure-activity relationships established that the compound 8n stands on a pinnacle of potent activity, with most structural variations having a deactivating in vitro effect. Mechanistically, this new series of agents contrasts with the previously reported 2-(4-aminophenyl)benzothiazoles; compound 8n is not reliant on induction of CYP1A1 expression for antitumor activity.