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In this study, a series of N-substituted 2-aminobenzothiazoles was prepared according to a recently developed method. Twelve compounds were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia

A simple and highly practical method for the synthesis of 2-N-substituted benzothiazoles has been developed by using nanocopper oxide as a recyclable catalyst. The present tandem process allows to get access to a wide range of 2-N-substituted benzothiazoles in good to excellent yields by the reaction of 2-iodo aniline with carbon disulfide and piperidine in presence of KOH as a base and DMSO as a solvent under ligand-free conditions.

A facile and convenient method was developed for the formation of novel N substituted 2-aminobenzothiazoles via an iron-catalysed condensation of 2-aminobenzothizole with different amines. This method is applicable for a wide range of aliphatic, aromatic and heterocyclic amines furnishing moderate yields of the corresponding products and thus rendering the methodology as a highly eco-friendly, inexpensive alternative to the existing methods.

In this paper, we report a unified approach to N-substituted and N,N-disubstituted benzothiazole (BT) sulfonamides. Our approach to BT-sulfonamides starts from simple commercially available building blocks (benzo[d]thiazole-2-thiol and primary and secondary amines) that are connected via (a) a S oxidation/S-N coupling approach, (b) a S-N coupling/S-oxidation sequence, or via (c) a S-oxidation/S-F bond formation/SuFEx approach. The labile N-H bond in N-monoalkylated BT-sulfonamides (pKa (BTSO2N(H)Bn) = 3.34 ± 0.05) further allowed us to develop a simple weak base-promoted N-alkylation method and a stereoselective microwave-promoted Fukuyama-Mitsunobu reaction. N-Alkyl-N-aryl BT-sulfonamides were accessed with the help of the Chan-Lam coupling reaction. Developed methods were further used in stereo and chemoselective transformations of podophyllotoxin and several amino alcohols.

The present invention features compounds useful in the treatment of neurological disorders. The compounds of the invention, alone or in combination with other pharmaceutically active agents, can be used for treating or preventing neurological disorders.

At present, there are many sulfur-containing drugs used for treating various diseases in the market, such as antipsychotic drug chloropropylthiophene; and sulfide has a wide biological activity, and not only can be easily converted into other types of sul

2-Aminobenzothiazoles comprise a valuable structural motif, which prevails in versatile natural products and biologically active compounds. Herein, a switchable and scalable C-N coupling protocol was developed for the synthesis of these compounds from 2-chlorobenzothiazoles and primary amines. Gratifyingly, this protocol was achieved under transition-metal-free and solvent-free conditions. Moreover, introducing an appropriate amount of NaH completely switched the selectivity from mono- toward di-heteroarylation, and further investigations provided a rationale for this new finding. Furthermore, gram-scale synthesis of representative products 3a and 4a was realized by applying operationally simple and glovebox-free procedures, which revealed the practical usefulness of this work. Finally, evaluation of the quantitative green metrics provided evidence that our protocol was superior over the literature ones in terms of green chemistry and sustainability.

Buchwald-Hartwig amination of chloroheteroarenes has been a challenging synthetic process, with very few protocols promoting this important transformation at ambient temperature. The current report discusses about an efficient copper-based catalytic system (Cu/PTABS) for the amination of chloroheteroarenes at ambient temperature in water as the sole reaction solvent, a combination that is first to be reported. A wide variety of chloroheteroarenes could be coupled efficiently with primary and secondary amines as well as selected amino acid esters under mild reaction conditions. Catalytic efficiency of the developed protocol also promotes late-stage functionalization of active pharmaceutical ingredients (APIs) such as antibiotics (floxacins) and anticancer drugs. The catalytic system also performs efficiently at a very low concentration of 0.0001 mol % (TON = 980,000) and can be recycled 12 times without any appreciable loss in activity. Theoretical calculations reveal that the π-acceptor ability of the ligand PTABS is the main reason for the appreciably high reactivity of the catalytic system. Preliminary characterization of the catalytic species in the reaction was carried out using UV-VIS and ESR spectroscopy, providing evidence for the Cu(II) oxidation state.

Iron-catalyzed oxidative amination of benzylic C(sp3)–H bonds with anilines bearing electron-withdrawing groups (EWGs) or electron-donating groups (EDGs) is realized based on simple variations of N-substituents on imidazolium cations in novel ionic Fe(III) complexes. The structural modification of the imidazolium cation resulted in regulation of the redox potential and the catalytic performance of the iron metal center. Using DTBP as oxidant, [HItBu][FeBr4] showed the highest catalytic activity for anilines bearing EWGs, while [HIPym][FeBr4] was more efficient for EDG-substituted anilines. This work provides alternative access to benzylamines with the advantages of both a wide substrate scope and iron catalysis.

Reactions of (2-(pyren-1-ylmethylene)hydrazinyl)benzothiazole (L) with ruthenium(II) prefabricated precursors [RuHCl(CO)(EPh3)3] and [RuH2(CO)(EPh3)3] (E = P or As) afforded new Ru(II) complexes [RuCl(CO)(EPh3)2(L)] and [RuH(CO)(EPh3)2(L)] (E = P or As) (1–4). All the Ru(II) complexes (1–4) were characterized by IR, NMR spectroscopies, ESI-mass spectrometry and elemental analyses. The solid-state structures of Ru(II) complexes (2 and 3) were established by single crystal X-ray analyses and revealed distorted octahedral geometries around the ruthenium(II) ion and mono anionic bidentate N^N coordination mode for hydrazine ligand. The Ru(II) complexes 2 and 3 were also analyzed using Hirshfeld surface analysis and DFT calculations. Moreover, all the complexes (1–4) were utilized in the N-alkylation reactions of amines using alcohol. Complex 3 was found to be highly active towards N-alkylation of different aromatic amines with alcohol.

A series of ruthenium(II) complexes (1–6) of pyridine-carboxamide ligands, HLBT/BI (HLBT = N-(benzo[d]thiazol-2-yl)picolinamide and HLBI = N-(1H-benzo[d]imidazol-2-yl)picolinamide), have been synthesized. All Ru(II) complexes have been characterized by using various spectroscopic techniques (FTIR, UV–Visible, 1H, 13C, 31P NMR and ESI-MS), conductivity and elemental analyses. The solid-state structures of all Ru(II) complexes, except 2, were substantiated by the single crystal X-ray diffraction technique that revealed versatile coordination modes of two bidentate ligands varying between N–N and N–O modes. All Ru(II) complexes exhibited a distorted octahedral geometry with a bidentate ligand while other coordination sites are occupied by either anionic Cl? or neutral co-ligands (CO, PPh3, CH3CN or (CH3)2SO). These well-defined ruthenium(II) complexes have been utilized as the homogeneous catalysts for the alkylation of amines using alcohols ensuing hydrogen borrowing strategy. Out of six complexes, 1 and 2 were found highly effective catalysts towards the N-alkylation of different amines with assorted alcohols. The alkylated products were obtained in excellent yields with good tolerance to a large variety of functional groups. To evaluate the role of putative Ru-hydride species as the intermediate during the catalytic cycle, the respective Ru-H complexes (7 and 8) were synthesized by the reaction of complexes 1 and 2 with NaBH4. Both Ru-H complexes were characterized using different spectroscopic techniques and crystallography. Importantly, both Ru-H complexes, 7 and 8, were directly able to alkylate imine using alcohol thus confirming the involvement of Ru-hydride species as the intermediates during the proposed catalytic cycle.

The invention provides a synthetic method for N-alkyl(benzo)thiazole. The synthetic method comprises the following steps: putting 0.4-0.8 mmol of a carbonyl compound, 0.4-0.8 mmol of p-toluenesulfonylhydrazide and 4-10 mL of a solvent in a flask and carrying out a reaction at 30 DEG C to 80 DEG C for 1 to 3 h; adding 0.4 mmol of 2-aminothiazole, 0.4-0.8 mmol of metal copper salt and 0.4-1.2 mmolof an alkali substance into the above reaction system, carrying out heating to 100 DEG C to 150 DEG C, and continuing the reaction for 2 h to 5 h; terminating the reaction to obtain a reaction productA; and subjecting the product A to purification and impurity separation so as to obtain pure N-alkyl(benzo)thiazole. According to the invention, the intermediate sulfonyl hydrazone is prepared from the carbonyl compound and sulfonyl hydrazide, and reacts with a 2-aminothiazole substance in the presence of a catalyst and under alkali conditions to obtain N-alkyl(benzo)thiazole. The synthetic method of the invention has the advantages of simple operation, low cost, high product yield and wide application range of a substrate. At the same time, the established method can also realize the synthesis of the anti-inflammatory drug fanetizole, and thus has high practical value.

An efficient and practical C–N bond formation methodology for the synthesis of N-alkylated (benzo)thiazoles was developed, via the copper-catalyzed one-pot two-step reactions of 2-amino(benzo)thiazoles and aldehydes (ketones) with tosylhydrazide. This cross-coupling reaction proceeded smoothly and tolerated a broad range of functional groups (46 examples). A variety of functionalized N-alkylated (benzo)thiazoles were obtained in moderate to high yields. Notably, gram-scale synthesis of fanetizole (anti-inflammatory drug) was also realized through this protocol.

The catalytic activity of snowman-like and core-shell Fe3O4/Au nanoparticles (NPs), obtained through a “wet chemistry” approach which directly restitutes nanocatalysts stable and highly active in the reaction medium, was tested towards N-alkylation reactions. The nanocatalysts were tested for the synthesis of secondary amines. The core-shell NPs, thanks to the surface properties, homogeneous dispersion and intimate connection with reagents in the catalyst medium, exhibited an excellent catalytic activity (e. g. >99 % yield and conversion of aniline in very short time and mild conditions). Owing to the magnetic part, the nanoparticles can be easily separated and reused, showing an almost stable activity after 10 cycles.

Direct reaction of isocyanides with some sulfenic-acid-generating sulfoxides led to the effective formation of the corresponding thiocarbamic acid S-esters in good to high yields. A multicomponent reaction involving isocyanide, sulfoxide, and a suitable nucleophile has also been developed, providing ready access to a diverse range of sulfur-containing compounds, including isothioureas, carbonimidothioic acid esters, and carboximidothioic acid esters.

In the aspect of more effective ruthenium based catalyst design, three new ruthenium(II) phosphino-hydrazone/thiosemicarbazone complexes (1–3) have been synthesized by the reactions of cis-[RuCl2(dmso)4] or [RuHCl(CO)(AsPh3)3] with deprotonated 2-(2-(diphenylphosphino)benzylidene)-2-thiophenecarboxylic acid hydrazone (PNO-Thy) or 2-(2-(diphenylphosphino)benzylidene)-4-phenyl-3-thiosemicarbazone (PNS-Ph). The structures of the complexes (2 and 3) were established by X-ray crystallography and spectroscopic methods including elemental analysis, FT-IR and NMR (1H, 13C & 31P). Single crystal XRD upshots of complexes (2 and 3) revealed a distorted octahedral geometry around the ruthenium ion with hydrazone/thiosemicarbazone acts as a monoanionic tridentate PNO/PNS donor fashion. The catalytic study of complexes 1–3 towards regioselective N-alkylation reactions of amines was completed, showing that all catalysts are active toward catalytic transformations. Notably, complex 3 was found to be very efficient catalysts toward N-alkylation of a wide range of heterocyclic amines with alcohols. This catalysis provides a clean, convenient and practical route for the direct N-alkyl amine synthesis.

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.

The invention discloses a preparation method of 2-aminobenzothiazole compounds. The 2-aminobenzothiazole compounds is prepared from the following steps of dissolving phenyl/naphthalene isothiocyanateand primary amine into a solvent, adding a catalyst iodine and an oxidant, carrying out one-pot multi-step tandem reaction to prepare the 2-aminobenzothiazole compounds under the temperature of 80 to 150 DEG C. The synthesis method has the advantages that raw materials are cheap and easily available, the reaction condition is mild, the substrate application range is broad, atom economy is high, requirements of green chemical are met, and a novel method which is economical and practical and green and environmentally friendly is provided for synthesis of the 2-aminobenzothiazole compounds.

The invention discloses a method for synthesizing substituent miscellaneous aromatic amine through a reaction between miscellaneous aromatic amine and amine. Inorganic base serves as an accelerant. The miscellaneous aromatic amine and the amine are directly subjected to the de-ammonia gas alkylation reaction, N-substituent miscellaneous aromatic amine ramifications are obtained, the reaction temperature ranges from 130 DEG C to 200 DEG C, the reaction time ranges from 24 hours to 48 hours, and the by-product is ammonia gas. According to the technical scheme, the inorganic base serves as the accelerant, the amine low in price and easy to get serves as an alkylation reagent, under the solvent-free conditions of nitrogen protection and sealing, the miscellaneous aromatic amine and the amine are subjected to the de-ammonia gas N-alkylation reaction, and the N-substituent miscellaneous aromatic amine ramifications can be obtained through direct synthesizing. The reaction method is direct, conditions are simple, operation is easy, the by-product is ammonia gas, less pollution is caused, and the ammonia gas can be recycled.

Three new heteroleptic copper(I) complexes [Cu(PPh3)(PNS-H)] (1) (PNS-H?=?2-(2-(diphenylphosphino)benzylidene) thiosemicarbazone), [Cu(PPh3)(PNS-Me)] (2) (PNS-Me?=?2-(2-(diphenylphosphino)benzylidene)-4-methyl-3-thiosemicarbazone) and [Cu(PPh3)(PNS-Et)] (3) (PNS-Et?=?2-(2-(diphenylphosphino)benzylidene)-4-ethyl-3-thiosemicarbazone) have been synthesized and characterized by various spectral and analytical technique. The single-crystal X-ray diffraction study of complexes 2 and 3 confirmed the formation of complexes with Cu(I) ion, coordinated through P,N,S-donor atoms from the phosphino-thiosemicarbazone ligands. All the copper(I) complexes have been demonstrated as highly efficient catalysts for the synthesis of N-alkylated heterocyclic amine by the coupling of primary amines with alcohols at low catalyst loading, and the maximum yield was obtained up to 99%. The N-alkylation reactions were readily carried out under moderate conditions, and release of water was the only by-product. In addition, the effects of substituent's on the ligand, solvents, base and catalyst loading on the catalytic activity of the complexes have also been investigated. Advantageously, only one equivalent of the alcohol was consumed in the process.

Simple pyrazole based palladacycle-phosphine with a high turnover has been developed and applied for the N-alkylation of amines and sulfanilamide using alcohols as substrates by hydrogen borrowing strategy. N-alkylation of primary and secondary amines resulted in high isolated yields at 100–130 °C, under solvent free conditions. More challenging secondary aliphatic as well as aromatic alcohols were also successfully utilized as alkylating agents under similar reaction conditions. The turn over number reached up to 43000 for N-benzylation of aniline using benzyl alcohol. Notably, regioselective N-alkylation of 2-aminobenzothiazole and 4-aminobenzenesulfonamide to the corresponding 2-N-(alkylamino)azoles and 4-amino-(N-alkyl)benzenesulfonamides using alcohols as alkylating agents have been achieved using our new pre-catalyst-phosphine system.

An iodine-catalyzed formation of substituted 2-aminobenzothiazole derivatives is herein described using hydrogen peroxide as an oxidant in PEG400. The method enabled an efficient environmentally sound access to this valuable scaffold in moderate to excellent yields under metal-free conditions.

Conditions for the palladium-NHC-catalyzed amination of aryl sulfides with aliphatic as well as aromatic amines were established. The KHMDS-mediated amination of heteroaryl sulfides could proceed without palladium. Based on the distinct difference in reactivity of C-Br and C-S bonds, a sequential amination of bromothioanisole can take place to install two different alkylamino groups onto the aromatic ring in one pot. A palladium-NHC precatalyst shows high efficiency for C-S bond cleavage for the amination of aryl sulfides with aliphatic amines or aromatic amines.

A series of ruthenium(II) complexes incorporating a thiosemicarbazone chelate tethered with a diphenylphosphine pendant have been studied. Thus, [(PNS-Et)RuCl(CO)(PPh3)] (1), [N,S-(PNS-Et)RuH(CO)(PPh3)2] (2) and [(PNS-Et)RuCl(PPh3)] (3) were synthesized by reactions of various RuII precursors with 2-(2-(diphenylphosphino)benzylidene)-N-ethylthiosemicarbazone (PNS-Et). However, complexation of PNS-Et with an equimolar amount of [RuCl2(dmso)4] resulted in two different entities [(PNS-Et)RuCl(dmso)2] (4) and [(PNS-Et)2Ru] (5) with different structural features in a single reaction. All the RuII complexes have been characterized by analytical and various spectroscopic techniques. Compounds 1-5 were recrystallized, and the X-ray crystal structures have been reported for 1, 2 and 5. In the complexes 1 and 3-5 the ligand coordinated in a tridentate monobasic fashion by forming PNS five- and six-membered rings, whereas in 2, the ligand coordinated in a bidentate monobasic fashion by forming a strained NS four-membered ring. Furthermore, compounds 1-5 showed catalytic activity in N-alkylation of heteroaromatic amines. Notably, complexes 1-3 were found to be very efficient catalysts toward N-alkylation of a wide range of heterocyclic amines with alcohols. In the presence of a catalytic amount of 2 with 50 mol% of KOH, N1,C5-dialkylation of 4-phenylthiazol-2-amine has been investigated. Reaction of in situ generated aldehyde with amine yields the N1,C5-dialkylated products through the hydride ion transformation from alcohol. Complexes 1-3 also catalyzed a variety of coupling reactions of benzyl alcohols and sulfonamides, which were realized often with 99% isolated yields. Advantageously, only one equivalent of the primary alcohol was consumed in the process.

A series of phosphine-functionalized hydrazone/thiosemicarbazone ligands and their corresponding ruthenium(II) carbonyl complexes of the type [RuCl(CO)(AsPh3)(L)] (1-5) [L = 2-(2-(diphenylphosphino)benzylidene)benzoic acid hydrazone (PNO-BHy), 2-(2-(diphenylphosphino)benzylidene)nicotinic acid hydrazone (PNO-NHy), 2-(2-(diphenylphosphino)benzylidene)-2-furoic hydrazone (PNO-FHy), 2-(2-(diphenylphosphino)benzylidene)-4-ethyl-3-thiosemicarbazone (PNS-EtTs), 2-(2-(diphenylphosphino)benzylidene)-4-cyclohexyl-3-thiosemicarbazone (PNS-CyTs)] have been synthesized based on the ligands with different electronic and steric effects. These complexes were characterized by elemental analyses and various spectral methods. The solid-state structure of the complex 4 was determined by single-crystal X-ray diffraction method. In all of the complexes, the ligand was bound to the Ru(II) center via the PNO/PNS donor atoms. All the ruthenium(II) complexes were demonstrated as highly efficient catalysts for the synthesis of secondary amines/amides by the coupling of primary amines/amides with alcohols at low catalyst loading, and the maximum yield was obtained up to 98%. The N-alkylation reaction can be readily carried out under moderate conditions, and release of water is the sole byproduct. In addition, the effects of substituents on the ligand, solvents, base and catalyst loading on the catalytic activity of the complexes have been investigated. Advantageously, only one equivalent of the alcohol was consumed in the process.

Catalyst-free autocatalyzed dehydrative N-alkylation reactions of 2-aminobenzothiazoles, 2-aminopyrimidines, and 2-aminopyrazine with primary and secondary alcohols have been achieved for efficient, practical, and green synthesis of the versatile heteroaryl amine derivatives. These reactions were interestingly induced by structure-dependent tautomeric equilibria of the heteroaryl amines via MPV-O transfer hydrogenation of the imino tautomers by alcohols to give aldehydes as the key initiating step.

An efficient copper-catalyzed method for the synthesis of a variety of 2-aminobenzothiazoles has been developed. The reaction proceeded from carbodiimide and sodium hydrosulfide via a tandem reaction in the presence of copper(ii) trifluoromethanesulfonate to afford the corresponding 2-aminobenzothiazole derivatives in good to perfect yields. This journal is the Partner Organisations 2014.

Ruthenium(ii) carbonyl complexes with phosphine-functionalized PNS type thiosemicarbazone ligands [RuCl(CO)(EPh3)(L)] (1-6) (E = P or As, L = 2-(2-(diphenylphosphino)benzylidene) thiosemicarbazone (PNS-H), 2-(2-(diphenylphosphino)benzylidene)-N-methylthiosemicarbazone (PNS-Me), 2-(2-(diphenylphosphino)benzylidene)-N-phenylthiosemicarbazone (PNS-Ph)) have been synthesized and characterized by elemental analysis and spectroscopy (IR, UV-Vis, 1H, 13C, 31P-NMR) as well as ESI mass spectrometry. The molecular structures of complexes 1, 2 and 6 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that all the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate PNS fashion. All the ruthenium complexes (1-6) were tested as catalyst for N-alkylation of heteroaromatic amines with alcohols. Notably, complex 2 was found to be a very efficient and versatile catalyst towards N-alkylation of a wide range of heterocyclic amines with alcohols. Complex 2 can also catalyze the direct amination of 2-nitropyridine with benzyl alcohol to the corresponding secondary amine. Furthermore, a preliminary examination of performance for N,N-dialkylation of diamine showed promising results, giving good conversion and high selectivity. In addition, N-alkylation of ortho-substituted anilines (-NH2, -OH and -SH) led to the one-pot synthesis of 2-aryl substituted benzimidazoles, benzoxazoles and benzothiazoles, also revealing the catalytic activity of complex 2. This journal is the Partner Organisations 2014.

Copper/N,N,N',N'-tetramethylethylenediamine (Cu/TMEDA)-catalyzed ambient temperature tandem reactions of isothiocyanates with 2-iodophenols or 2-iodoanilines in water without the protection of an inert atmosphere are described, which provide a simple, rapid, environmental method for the synthesis of a variety of 2-iminobenzo-1, 3- oxathioles and 2-aminobenzothiazoles in good yields. More important, the present reaction process needs only low amounts of copper catalyst (1mol%) and can yield the products on a gram scale.

A simple, scalable, ligand-free, and metal-free protocol for arylation of amines and monoarylation of symmetrical diamines with diheteroaryl halides in the presence of brine solution has been developed. The protocol has broad structural applicability for chemoselective monoarylation of a wide variety of symmetrical, cyclic, and acyclic aliphatic diamines. The protocol is also applicable for selective arylation of aliphatic amine in the presence of aromatic amine.

An efficient and versatile iron phthalocyanine catalyzed method has been developed for N-alkylation of various amines with alcohols. Readily available alcohols were used as alkylating agents for direct N-alkylation of aminobenzothiazoles, aminopyridines and aminopyrimidines. N-Alkylation of ortho-substituted anilines (-NH2, -SH and -OH) led to the synthesis of 2-substituted benzimidazoles, benzothiazoles and benzoxazoles in one pot.

Cobalt catalysis: Synthesis of substituted 2-aminobenzimidazoles, 2-aminobenzothiazoles, and 2-aminobenzoxazoles was achieved by using cobalt(II) acetate catalyzed isocyanide insertion to o-diaminobenzene, 2-aminobenzenethiol, and 2-aminophenol derivatives in 1,4-dioxane (see scheme). It was found that the reaction proceeded efficiently to give the desired products in up to 95 % isolated yields by C-N and C-S (O, N) formation in a single step. Copyright

A novel solid-phase methodology has been developed for the synthesis of N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo[d]thiazole resins 5 by cyclization reaction of 2-iodophenyl thiourea resin 3. The resin-bound 2-iodophenyl thiourea 3 is produced by addition of 2-iodophenyl isothiocyanate 2 to the amine-terminated linker amide resin 1. These core skeleton 2-aminobenzo[d]thiazole resins 5 undergo functionalization reactions with various electrophiles, such as alkyl halides, acid chlorides, and sulfonyl chlorides to generate N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole resins 6, 7, and 8, respectively. Finally, N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives 9, 10, and 11 are then generated in good yields and purities by cleavage of the respective resins 6, 7, and 8 using trifluoroacetic acid (TFA) in dichloromethane (DCM).

In contrast to the borrowing hydrogen-type N-alkylation reactions, in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the addition of external aldehydes was accidentally found to be a simple and effective protocol for alcohol activation. This interesting finding subsequently led to an efficient and green, practical and scalable aldehyde-catalyzed transition metal-free dehydrative N-alkylation method for a variety of amides, amines, and alcohols. Mechanistic studies revealed that this reaction most possibly proceeds via a simple but interesting transition metal-free relay race mechanism. Copyright

In the presence of a catalytic amount of NaOH, the selective N-alkylation of various heteroaromatic primary amines is reported. With 1 equiv of NaOH, N1,C5-dialkylation of 4-phenyl-2-aminothiazoles has been investigated. Reaction of in situ generated aldehyde with amine yields the N-alkylated and N1,C5-dialkylated products through hydride ion transformation from alcohol.

An unexpected diazabicyclo[5.4.0]undec-7-ene (DBU) catalysed rate enhancement of N-arylation of amines with diheteroaryl halides is reported. DBU is found to activate the Ar-Cl bond of a diheteroaryl halide, forming a green coloured adduct under neat conditions. The activated green coloured adduct was used for the arylation of amines under neat conditions and was found to be the fastest diheteroarylating agent reported to date. The Royal Society of Chemistry 2013.

Two efficient methods for the amination of 2-halothiazoles are presented here. A first protocol requires a Pd/L system. Several 2-aminothiazoles were synthesized under optimized conditions and isolated in good yields. The first palladium-catalyzed C-N coupling reactions between 2-halothiazoles and primary alkylamines are presented. In a second part, ligand-free copper-catalyzed aminations of 2-halothiazoles by alkylamines and aniline in a green solvent have been developed. The protocol is very effective for primary and secondary amines and perfectly tolerates the presence of another halide moiety on the 2-halothiazole. The reaction occurs under the assistance of microwave irradiation, which drastically decreases the reaction time. The reaction leads to the formation of 2-aminothiazoles, key molecules in pharmaceutical research. Copyright

Coloured disubstituted benzoquinonimine trimeric structures are obtained as main reaction products of the oxidation of p-electron donor pri-mary aromatic amines using two different laccases, CotA-laccase from Baccilus subtilus and TvL from Trametes versicolor. These orange-red to purple products, presenting high molar extinction coeffi-cients, presumably result from oxidative homocou-pling reactions, through the formation of N-C bonds at positions 2 and 5, of the laccase oxidised inter-mediate as showed in the proposed oxidative path-way. The product of 1,4-phenylenediamine is shown to be the trimer known as Bandrowski's base which has an established role in hair and fur dyeing. Our results also show that the occurrence and/or rates of oxidation of aromatic amines are strongly dependent on the presence of p-electron releasing substituents in the aromatic ring and are independent on the properties of the enzyme used. Overall our data con-tribute for (i) understanding key features of laccase reactivity with p-substituted aromatic amines and (ii) establishing enzymatic processes that lead to the syn-thesis of coloured bio-products under mild condi-tions with potential impact in the cosmetic and dye industries.

An "on-water" one-pot process has been engineered for the preparation of 2-aminobenzothiazole from ortho-halo (-F, -Cl, -Br and -I) substituted unsymmetrical thioureas. For ortho -I and -Br substrates the reactions afford 2-aminobenzothiazoles under metal free condition promoted by base. However, the relatively inert ortho -Cl and -F substrates undergo intramolecular arylthiolation only in the presence of CuO nanoparticles yielding 2-aminobenzothiazoles. This methodology provides easy access to aminobenzothiazoles utilising even the ortho -Cl and -F substrates. The catalyst is recyclable several times without loss of substantial activity. Other remarkable features include the wide range of functional group tolerance, absence of chromatographic purification (for ortho -I and -Br substrates) and providing moderate to excellent yield of the products under mild conditions, thus rendering the methodology as a highly eco-friendly alternative to the existing methods.

The direct and regioselective N-alkylation of amino-azoles to the corresponding 2-N-(alkylamino)azoles using various alcohols as alkylating agents with good to excellent yields has been accomplished by an iridium complex/base system.

The 1,10-phenanthroline-catalyzed tandem reaction of 2-iodoaniline with isothiocyanate in water is described, which provides an environmentally benign, efficient and simple route for the preparation of 2-aminobenzothiazoles. The present tandem process shows broad substrate scope in the absence of transition metals and phase-transfer catalysts. Copyright

Iron was used as the catalyst for the direct C-H functionalization/C-S bond formation under mild conditions. Various substrates could afford benzothiazoles in moderate to excellent yields. Preliminary mechanistic studies revealed that pyridine played a crucial role for the high yields and selectivities.

The preparation of 2-(N-alkylamino)benzothiazoles via regioselecive N-alkylation of 2-aminobenzothiazoles has been accomplished by using benzylic alcohols as alkylating agents.

Palladium(II) acetate is a versatile, inexpensive, and simple catalyst for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines as well as carboxamides, sulfonamides, and phosphazenes, using, in all cases, primary alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. The regioselectivity of the benzothiazol-2-amine alkylation is contrary to that found using halogenated electrophiles.

Tandem reactions of isothiocyanates (1) with 2-aminothiophenols (2), or isothiocyanates (1) with 2-aminophenols (4), were carried out rapidly and efficiently in water. A significant rate acceleration of the reaction between 1a and 2a in water compared wit

All in it together: A highly efficient and extremely versatile method for the assembly of benzothiazoles with a nitrogen substituent in the 2-position relies on a copper-catalyzed cascade reaction of a 2-haloaniline, carbon disulfide, and an N nucleophile (see scheme). The products are useful precursors for the synthesis of a range of important pharmaceutical agents. DMF=N,N-dimethylformamide; R,R=H, alkyl, aryl; Z=Me, CF3, CO 2Me, CN, N2O, Cl, F, Ac.

A ligand free, copper-catalyzed N-arylation reaction of amines with diheteroaryl halides in heterogeneous medium at room temperature has been developed. The protocol is very effective for low boiling amines and useful for amines available in aqueous solution. The reaction gives chemospecific arylation of amines with diheteroaryl halides in the mixture monoheteroaryl halides, diheteroaryl halides and carbocyclic aryl halides. The reaction is also chemospecific with respect to arylation of aliphatic amines. Monoarylated piperazines were also synthesized at room temperature following this protocol. The Royal Society of Chemistry 2011.

An efficient, economical, and convenient method was developed for the preparation of 2-substituted (N, O, C) benzothiazoles from N′-substituted- N-(2-halophenyl)thioureas, O′-substituted-N-(2-halophenyl) carbamothioates, or N-(2-halophenyl) thioamides via a base-promoted cyclization in dioxane without any transition metal. A one-pot variant combining the synthesis of the thiourea and the cyclization was also demonstrated. High yields were obtained, and a variety of functional groups were tolerated under these conditions. Transition-metal-free, mild reactive conditions, wide application scope, and shorter reaction times make this method superior to the reported methods for the synthesis of 2-substituted benzothiazoles and suitable for combinatorial format.

A ligand-free copper-catalyzed reaction of 2-halobenzenamines with isothiocyanates has been developed for the synthesis of 2-aminobenzothiazoles. In the presence of CuBr and TBAB (tetra-n-butyl ammonium bromide, additive), a variety of 2-halobenzenamines underwent the reaction with isothiocyanates at 40 °C, affording 2-aminobenzothiazoles in moderate to excellent yields. It is noteworthy that the reaction is conducted under mild, relatively low catalyst loading, and ligand- and base-free conditions.

Molecular oxygen (O2) was successfully employed as a reoxidant in cyclizations of thiobenzanilides 1a-s through a palladium-catalyzed C-H functionalization/intramolecular C-S bond formation process, leading to an efficient, green method for the synthesis of 2-arylbenzothiazoles 2a-s. Addition of cesium fluoride (CsF) greatly enhanced the reactions, which produced variously substituted 2-arylbenzothiazoles with good functional group tolerance. Thioureas 4a-j were also found to be suitable substrates for the cyclization process using a palladium/O2 catalyst system, thus generating 2-aminobenzothiazoles 5a-j. One-pot syntheses of 2-aminobenzothiazoles 5a-j from aryl isothiocyanates 6 and amines 7 were also successful.