Aerobic Copper-Mediated Domino Three-Component Approach to 2-Aminobenzothiazole Derivatives

Se-S dynamic exchange reaction: a strategy of highly efficient S-S bond cleavage for synthesizing benzothiazole derivatives

We report a Se-S dynamic exchange reaction as a methodology for highly efficient S-S bond cleavage. In this study, a Na2Se-disulfide dynamic exchange reaction has been demonstrated for the first time and the strategy has been employed in the preparation of benzothiazole derivatives, demonstrating highly efficient S-S bond cleavage, lowered dosage of the S-S bond cleaving reagent, good tolerance toward various substituents and excellent yields. It is envisaged that the concept of metal selenide-disulfide dynamic interchange reaction is a general avenue for synthesizing sulfur-containing heterocycles.

Recent Advancement on the Indirect or Combined Alternative Thiocyanate Sources for the Construction of S-CN Bonds

The process of thiocyanation is a notable chemical conversion owing to the extensive range of applications associated with thiocyanate compounds in the field of organic chemistry. In past centuries, the thiocyanation reaction incorporated metal thiocyanates or thiocyanate salts as sources of thiocyanate, which are environmentally detrimental and undesirable. In recent literature, there have been numerous instances where combined or indirect alternative sources of thiocyanate have been employed as agents for thiocyanation, showcasing their noteworthy applications. The present literature review focuses on elucidating the ramifications associated with the utilization of indirect or combined alternative sources of thiocyanate in various thiocyanation reactions.

Synthesis and Biological Importance of 2-(thio)ureabenzothiazoles

The (thio)urea and benzothiazole (BT) derivatives have been shown to have a broad spectrum of biological activities. These groups, when bonded, result in the 2-(thio)ureabenzothizoles (TBT and UBT), which could favor the physicochemical and biological properties. UBTs and TBTs are compounds of great importance in medicinal chemistry. For instance, Frentizole is a UBT derivative used for the treatment of rheumatoid arthritis and systemic lupus erythematosus. The UBTs Bentaluron and Bethabenthiazuron are commercial fungicides used as wood preservatives and herbicides in winter corn crops. On these bases, we prepared this bibliography review, which covers chemical aspects of UBTs and TBTs as potential therapeutic agents as well as their studies on the mechanisms of a variety of pharmacological activities. This work covers synthetic methodologies from 1935 to nowadays, highlighting the most recent approaches to afford UBTs and TBTs with a variety of substituents as illustrated in 42 schemes and 13 figures and concluded with 187 references. In addition, this interesting review is designed on chemical reactions of 2-aminobenzothiazoles (2ABTs) with (thio)phosgenes, iso(thio)cyanates, 1,1′-(thio)carbonyldiimidazoles [(T)CDI]s, (thio)carbamoyl chlorides, and carbon disulfide. This topic will provide information of utility for medicinal chemists dedicated to the design and synthesis of this class of compounds to be tested with respect to their biological activities and be proposed as new pharmacophores.

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives

The review is devoted to modern trends in the chemistry of 2-amino and 2-mercapto substituted benzothiazoles covering the literature since 2015. The reviewed heterocycles belong to biologically active and industrially demanded compounds. Newly developed synthesis methods can be divided into conventional multistep processes and one-pot, atom economy procedures, realized using green chemistry principles and simple reagents. The easy functionalization of the 2-NH2 and 2-SH groups and the benzene ring of the benzothiazole moiety allows considering them as highly reactive building blocks for organic and organoelement synthesis, including the synthesis of pharmacologically active heterocycles. The review provides a summary of findings, which may be useful for developing new drugs and materials and new synthetic approaches and patterns of reactivity.

Direct access to bis-S-heterocyclesviacopper-catalyzed three component tandem cyclization using S8as a sulfur source

An elemental sulfur atom donor strategy for constructing a thiophene-fused thiazole bis-S-heterocyclic skeletonviaCu-catalyzed three-component tandem cyclization has been developed.

Copper-catalyzed synthesis of 2-aminobenzothiazoles from 2-iodophenyl isocyanides, potassium sulfide and amines

A simple and practically useful synthetic method for the synthesis of a variety of 2-aminobenzothiazoles was developed. This methodology could construct one C-N bond and two C-S bonds in a step reaction and provide the desired products in good to perfect yields.

Contemporary progress in the synthesis and reactions of 2-aminobenzothiazole: a review

Various protocols for the synthesis and reactions of 2-aminobenzothiazole.

Facile Fabrication of Ordered Component-Tunable Heterobimetallic Self-Assembly Nanosheet for Catalyzing "Click" Reaction

How to maximize the number of desirable active sites on the surface of the catalyst and minimize the number of sites promoting undesirable side reactions is currently an important research topic. In this study, a new way based on the synergism to achieve the successful fabrication of an ordered heterobimetallic self-assembled monolayer (denoted as BMSAM) with a controlled composition and an excellent orientation of metals in the monolayer was developed. BMSAM consisting of phenanthroline and Schiff-base groups was prepared, and its novel heterobimetallic (Cu and Pd) self-assembled monolayer anchored in silicon (denoted as Si-Fmp-Cu-Pd BMSAM) with a controlled composition and a fixed position was fabricated and characterized by UV, cyclic voltammetry, Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and water-drop contact angle (WDCA) analyses. The effects of Si-Fmp-Cu-Pd BMSAM on its catalytic properties were also systematically investigated using "click" reaction as a template by WDCA, XPS, SEM, XRD, ICP-AES and in situ Fourier transform infrared analyses in a heterogeneous system. The results showed that the excellent catalytic characteristic could be attributed to the partial (ordered or proper distance) isolation of active sites displaying high densities of specific atomic ensembles. The catalytic reaction mechanism of the click reaction interpreted that the catalytic process mainly occurred on the surface of the monolayer, internal active site (Pd) and rationalized that the Cu(I) species and Pd(0) reduced from the Cu(II) and Pd(II) catalyst were active species, which had a proper distance between two different metals. The cuprate-triazole intermediate and the palladium intermediate, whose production is the key step, should lie in a proper position between the copper and active palladium sites, with which the reaction rate of transmetalation would be improved to increase the amount of the undesired Sonogashira coupling product.

Metal-Free Synthesis of 2-Aminobenzothiazoles via Iodine-Catalyzed and Oxygen-Promoted Cascade Reactions of Isothiocyanatobenzenes with Amines

In this paper, a highly efficient and sustainable synthesis of 2-aminobenzothiazoles through the cascade reactions of isothiocyanatobenzenes with primary or secondary amines by using iodine as a catalyst and oxygen as an oxidant is presented. Mechanistically, the formation of the title compounds involves the in situ formation of the required benzothiourea intermediate followed by its intramolecular cross dehydrogenative coupling of a C(sp²)-H bond and a S-H bond. To our knowledge, this should be the first example in which 2-aminobenzothiazoles are efficiently prepared from simple and cheap isothiocyanates and amines under metal-free conditions by using iodine as a catalyst and molecular oxygen as an oxidant with water as the byproduct. Compared with literature protocols, this method eliminates the use of ortho-halo-substituted precursors, expensive transition-metal catalysts, and hazardous oxidants.