Synthesis of 2-mercaptobenzothiazoles via DBU-promoted tandem reaction of o-haloanilines and carbon disulfide

Recent advances in the radical cascade reaction for constructing nitrogen heterocycles using azides as radical acceptors

Due to the high conversion properties, azide compounds are widely utilized in organic synthesis. For instance, azide compounds readily release nitrogen to form a new N-C bond when they function as radical acceptors for the active intermediates in the reaction. Over the past decade, strategies employing azides as radical acceptors to construct nitrogen heterocycles have been extensively developed. This approach has emerged as a crucial method for synthesizing nitrogen heterocycles. Therefore, this paper provides a review of the research advancements in tandem cyclization reactions using azides as radical acceptors, summarizing the process of reaction design, exploration, reasoning of the mechanism, and prospects for further research of these reactions.

Microdroplet accelerated reaction for high-efficiency carbon disulfide conversion

Carbon disulfide (CS2) negatively impacts male sexual function and sperm quality. We propose an efficient method to convert CS2 into dithiocarbamic acid using electrospray ionization, achieving up to 96.7% conversion. Protonated CS2 intermediates (SCSH+) contribute to capturing CO2 in amine reactions. Moreover, the reaction efficiently converts CS2 from ethanol solution using microbubble bursting. This study lays the groundwork for accurate CS2 detection.

Metal-Free Temperature-Controlled Intermolecular [3 + 2] Annulation to Access Benzo[d]thiazole-2(3H)-thiones and Benzo[d]thiazol-2(3H)-ones

A facile access to benzo[d]thiazole-2(3H)-thiones and benzo[d]thiazol-2(3H)-ones has been developed through a temperature-controlled intermolecular [3 + 2] annulation of N,N-disubstituted arylhydrazines with CS₂ in the presence of DMSO. This protocol can obviate the prefunctionalization of the starting materials. This direct C-S/C-N bond formation reaction was performed in the absence of any external catalysts, transition metals, bases, ligands, and oxidants with high step economy.

Recent advances in the synthesis of benzothiazole and its derivatives

Abstract:

Benzothiazoles have recognized pharmacophores in the field of research, predominantly in synthetic and medicinal chemistry, on account of their significant pharmaceutical properties. This important class of derivatives endows an extensive range of biological activities like anti-inflammatory, antidiabetic, anticancer, anticonvulsant, antibacterial, antiviral, antioxidant, antituberculosis, enzyme inhibitors, etc. Hence, various methodologies have been accomplished to synthesize benzothiazole compounds considering the purity, yield, and selectivity of the products. This review provides different reaction methods that are involved in the synthesis of a variety of benzothiazole derivatives.

Transition-Metal-Free Synthesis of N-Arylphenothiazines through an N- and S-Arylation Sequence

An efficient synthetic method of N-arylphenothiazines from o-sulfanylanilines under transition-metal-free conditions is disclosed. An N- and S-arylation sequence of o-sulfanylanilines enabled us to synthesize a wide variety of N-arylphenothiazines. In particular, one-pot synthesis of N-arylphenothiazines was accomplished from easily available modules through preparation of o-sulfanylanilines by thioamination of aryne intermediates and following N- and S-arylation sequence.

Iodine-Catalyzed Synthesis of 3-Arylthioindoles Employing a 1-Aryltriazene/CS2 Combination as a New Sulfenylation Source

A practical approach for the regioselective synthesis of 3-arylthioindoles has been accomplished using a combination of 1-aryltriazene/CS₂ as a new sulfenylation source. The methodology employs molecular iodine as a catalyst and is compatible with a variety of structurally diverse reactants.

Self-assembly of silver nanoparticles through functionalization with coumarin-thiazole fused-ring thiol

Self-assembly of nanoscale building blocks plays a critical role for the edifice of functional nanomaterials. In this work coumarin based fused-ring heterocyclic thiol functionalized silver nanoparticle exhibiting large self-assembly is reported. The particles spontaneously self-organise towards the formation of larger superstructures, yet still retaining their individual particle morphology (~10nm). The π-stacking behaviour of coumarin based fused ring aromatic skeleton seems to play the key role for the induction of dense assembly in this hybrid nanoparticles. In the present work the anchoring group (thiol) is directly attached to the aromatic framework of the Coumarin-thiazole fused-ring, for easier electron flow between the metal and the aromatic ligand. The synthesized materials have been characterized by UV-Vis, Fluorescence, XRD, TEM, SAED, IR, 1H and 13C NMR. The synthesis of the ligand and process of functionalization is simple and easily reproducible.

Metal-free C-H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

A facile and effective C-H functionalization strategy for the synthesis of 2-mercaptobenzothiazoles and 2-mercaptobenzoxazoles is described. 1,3-Propanedithiol was employed to convert benzothiazoles and benzoxazoles to the corresponding heteroarylthiols in the presence of potassium hydroxide and DMSO. This novel protocol is featured by direct C-H mercaptalization of heteroarenes and a simple reaction system.

Green carbon disulfide surrogateviaa combination of potassium sulfide and chloroform for benzothiazine-thione and benzothiazole-thione construction

An efficient and green carbon disulfide surrogateviafacile combination of potassium sulfide and chloroform has been developed.

Switching Selectivity of α-Enolic Dithioesters: One Pot Access to Functionalized 1,2- and 1,3-Dithioles

An operationally simple cascade protocol has been developed for the construction of 1,2- and 1,3-dithiole derivatives from α-enolic dithioesters. 1,2-Dithioles are achieved by the reaction of dithioesters with elemental sulfur in the presence of InCl₃ under solvent-free conditions. 1,3-Dithioles have been constructed via DABCO mediated self-coupling of dithioesters in open air enabling the formation of two new C-S bonds and one ring in a single operation in contiguous fashion. The reactions proceeded smoothly affording the desired sulfur-rich heterocycles in good to excellent yields, exhibiting gram-scale ability and broad functional group tolerance utilizing easy to handle cheap and easily available reagents. The probable mechanisms for the formation of 1,2- and 1,3-dithioles from α-enolic dithioesters have been suggested.

Practical synthesis of symmetrical thioureas and heterocyclic thiones in water

A simple and practical protocol for the synthesis of symmetric thioureas and heterocyclic thiones has been developed. It involves the reaction of amines with phenyl chlorothionoformate in water to afford the symmetrical thioureas or heterocyclic thiones in good to excellent yields. Various amines including aromatic, aliphatic and chiral amines survived the reaction conditions. Mild conditions, simple work-up and high yields as well as using water as solvent are the major advantages of this protocol.

Recent advances in the chemistry and biology of benzothiazoles

Benzothiazole is a privileged heterocyclic scaffold having a benzene ring fused with a five-membered thiazole ring. This moiety has attracted considerable attention because of its wide range of pharmacological activities such as antitubercular, antimicrobial, antimalarial, anticonvulsant, anthelmintic, analgesic, anti-inflammatory, antidiabetic, antitumor activity, etc. In the last few years, some novel benzothiazoles have been developed with varied biological activities. To access this scaffold in high yield and to introduce diversity, a variety of new synthetic methods have been invented. In this review, we highlight the development of novel benzothiazoles for various biological activities along with the best synthetic protocols for their synthesis.

Ligand-free Cu-catalyzed odorless synthesis of unsymmetrical sulfides through cross-coupling reaction of aryl/benzyl/alkyl halides with an aryl boronic acid/S8 system as a thiolating agent in PEG

Efficient one-pot, one-step synthesis of unsymmetrical sulfides has been reported under mild reaction conditions with good yields in green solvent.

Metal-free DBU promoted regioselective synthesis of isoxazoles and isoxazolines

A new simple and efficient metal-free 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) promoted regioselective synthesis of 3,5-disubstituted isoxazoles and isoxazolines from aldoximes has been described.