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The present Letter describes the use of magnetically separable palladium–graphene nanocomposite, a complete magnetically separable catalyst for the synthesis of 2-alkyl quinolines via reaction of anilines with alkenyl ethers. Because of the uniform decoration of the Pd nanoparticles on support, the catalyst exhibited higher catalytic efficiency and it remains unaltered even after six repeated cycles.

A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The −NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.

Efficient, step-economic, Pd(II)-catalyzed one-pot sequential Sonogashira/Sonogashira, Sonogashira/Suzuki, Sonogashira/Heck, Suzuki/Sonogashira, Suzuki/Suzuki, Suzuki/Heck, Heck/Sonogashira, Heck/Suzuki and Heck/Heck cross coupling reactions of sterically hindered aryl/heteroaryl 1,2-dihalides have been developed. The present methodology allows the conversion of easily available aryl/heteroaryl 1,2-dihalides into synthetically useful unsymmetrically substituted arenes/heteroarenes in good to excellent yields under mild reaction conditions. This methodology is a powerful tool for building a versatile substrate which can be utilized for the synthesis of various organic scaffolds.

Organo-catalyzed aldol condensation of 2-hydroxyacetophenone and 4-nitrobenzaldehyde underwent regio- and enantioselective cyclization via intramolecular 5 -exo-trigonal cyclization to give 4-nitroaryl-3-benzofuranones. The product formation indicated that the proline bases (organocatalysts) suppressed the effect of carbonyl group by iminium ion formation and hence Michael addition is not possible. The conjugation effect moved toward 4-nitroaryl moiety suitable for 5 -exo-trig cyclization (Baldwin’s rule). Thus, the non-equilibrating intermediates (NEIs) which gave in enantio-enriched 3-benzofuranones. A high enantioselectivity (80–96.6%) was obtained with ( S )-pyrrolidinyl-tetrazole V under a metal-free condition.

Pyridazinones have drawn a substantial attention within the field of research analysis and development. The moiety is a subject matter of intensive research because of its wide spectrum of biological activities and therapeutic applications. The synthesis of pyridazinone and investigation of their chemical and biological activities have gained additional importance in recent years. In this review, we have compiled and discussed various biological and therapeutic potential of pyridazinone derivatives.

Reaction of the title substrates in the presence of MgI2 or Cu(O-Tf)2 leads to an efficient preparation of various highly functionalized cyclopentanes, generally with good to excellent diastereoselectivity.

Iodine has been recognized as an efficient, non-toxic, readily available and easy-to-handle electrophilic reagent to favour halocyclization reactions for the synthesis of novel iodofunctionalized heterocyclic molecules that serve as versatile intermediates in synthetic organic chemistry. This review presents numerous useful methodologies for the synthesis of O, N, S, and Se-heterocycles through electrophilic cyclization via the attack of an electrophile on the C(sp) bond of alkynes. The cyclization proceeds under mild reaction conditions and tolerates a wide variety of functional groups.

A series of novel heterocyclic analogs of chalcone containing isoxazole and a benzoxazinone ring as a prime motif was rationally designed and synthesized. There is nothing in the literature about such α,β-unsaturated ketones. These compounds were synthesized using a Claisen–Schmidt condensation reaction of the ketone precursor with different aromatic aldehydes using ethanol as solvent and piperidine as a base. Our procedure offers easy access to isoxazole and benzoxazinone based chalcone derivatives providing yields in the range of 81–93% within 16 min under mild conditions. Out of 21, 11 compounds were screened for their antibacterial activities. Among the screened compounds, compounds 5aj, 5ak and 5bj showed excellent antibacterial activities with MIC: 0.34, 0.59 and 0.74 mg ml−1 respectively as compared to standard drugs.

An efficient unprecedented Pd-catalyzed rapid 2-fluoroethoxylation of bromo-chalcones has been unveiled. The oxygen nucleophiles (fluoroalcohols) experience the rapid C O bond forming reaction for the first time, albeit the alcohols are known to be a weak nucleophile and have greater competing β–hydride elimination in the transition-metal-catalyzed (especially Pd and Cu) C O cross-coupling reaction. The higher fluoroalcohols have also been effectively coupled with bromo-chalcones with relatively lower rate.

Azadienes, generated in situ from o-aminobenzyl alcohols, undergo [4 + 2] cycloaddition reactions with a wide variety of alkynes to produce quinoline derivatives.

Base-mediated anti-Markovnikov additions of phenols onto terminal alkynes have been achieved. This paper presents insights into the role of DMSO in superbase-mediated chemo-, regio-, and stereoselective nucleophilic addition reactions of phenols onto aryl alkynes. Deuterium-labeling experiments uncover that the source of styryl protons in the products comes from the DMSO, not from the substrate (nucleophile) nor from the water workup. Competitive nucleophilic additions and the mechanistic pathway was corroborated by control experiments and computational calculations.

A catalytic system consisting of bis(4-methoxyphenyl)selenide and 4-(dimethylamino)pyridine (DMAP) has been developed for the regioselective synthesis of medium-sized bromo/iodo lactones and bromooxepanes possessing high transannular strain. (77)Se NMR, mass spectrometry and theoretical studies reveal that the reaction proceeds via a quaternary selenium intermediate.

A series of 3,7-diaryl-6,7-dihydro-5H-6-substituted-thiazolo[3,2-a]pyrimidin-5-ones (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j) were synthesized by the [4+2] cycloaddition reaction of 2-arylideneamino-4-arylthiazoles (2a–j) with in situ generated monosubstituted ketenes under PTC conditions coupled with ultrasonication in good to excellent yields. All the synthesized compounds were characterized on the basis of their spectral (IR, PMR, and Mass) and analytical data. The synthesized compounds were also screened for their insecticidal activity against Helicoverpa armigera and some of them showed promising activity.

Biomolecular structure elucidation is one of the major techniques for studying the basic processes of life. These processes get modulated, hindered or altered due to various causes like diseases, which is why biomolecular analysis and imaging play an important role in diagnosis, treatment prognosis and monitoring. Vibrational spectroscopy (IR and Raman), which is a molecular bond specific technique, can assist the researcher in chemical structure interpretation. Based on the combination with microscopy, vibrational microspectroscopy is currently emerging as an important tool for biomedical research, with a spatial resolution at the cellular and sub-cellular level. These techniques offer various advantages, enabling label-free, biomolecular fingerprinting in the native state. However, the complexity involved in deciphering the required information from a spectrum hampered their entry into the clinic. Today with the advent of automated algorithms, vibrational microspectroscopy excels in the field of spectropathology. However, researchers should be aware of how quantification based on absolute band intensities may be affected by instrumental parameters, sample thickness, water content, substrate backgrounds and other possible artefacts. In this review these practical issues and their effects on the quantification of biomolecules will be discussed in detail. In many cases ratiometric analysis can help to circumvent these problems and enable the quantitative study of biological samples, including ratiometric imaging in 1D, 2D and 3D. We provide an extensive overview from the recent scientific literature on IR and Raman band ratios used for studying biological systems and for disease diagnosis and treatment prognosis.

A novel Pd(II)-catalyzed approach for the direct synthesis of highly functionalized carbazoles from unprotected styrylindoles has been developed. The reaction features a variety of olefin substrates, which are readily switchable by subtle tuning of the reaction conditions. Investigations of the mechanism suggest that the C-H activation proceeds via enamine formation.

The formation of new C-C bond through highly regioselective ring opening of chalcone epoxides to nitrogen-containing heterocycles has been effectively worked out in impressive yields with heterocyclic nucleophiles such as pyrrole, indole, and 2-methyl indole in the presence of β-cyclodextrin using water as solvent at room temperature within 25–50 min. Water, an environmentally friendly reaction medium, has been utilized for the first time for the reaction of these heterocyclic nucleophiles with chalcone epoxides as their β-cyclodextrin complexes to afford 1,3-diaryl-2-hydroxy-3-(1H-3-indolyl/2-pyrrolyl)propan-1-ones (3a–u). The catalyst can be easily recovered and recycled for several times without loss of activity.

Triclosan (TCS) is a multi-purpose antimicrobial agent used as a common ingredient in everyday household personal care and consumer products. The expanded use of TCS provides a number of pathways for the compound to enter the environment and it has been detected in sewage treatment plant effluents; surface; ground and drinking water. The physico-chemical properties indicate the bioaccumulation and persistence potential of TCS in the environment. Hence, there is an increasing concern about the presence of TCS in the environment and its potential negative effects on human and animal health. Nevertheless, scarce monitoring data could be one reason for not prioritizing TCS as emerging contaminant. Conventional water and wastewater treatment processes are unable to completely remove the TCS and even form toxic intermediates. Considering the worldwide application of personal care products containing TCS and inefficient removal and its toxic effects on aquatic organisms, the compound should be considered on the priority list of emerging contaminants and its utilization in all products should be regulated.

Magnetic graphitic carbon nitride, Fe@g-C3N4, has been synthesized by adorning a graphitic carbon nitride (g-C3N4) support with iron oxide via non-covalent interaction. The magnetically recyclable catalyst showed excellent reactivity for the expeditious C-H activation and cyanation of amines.

Ongoing advances in nanotechnology research have established a variety of methods to synthesize nanoparticles (NPs) from a diverse range of materials, including metals, semiconductors, ceramics, metal oxides, polymers, etc. Depending upon their origin and synthesis methods, NPs possess unique physicochemical, structural and morphological characteristics, which are important in a wide variety of applications concomitant to electronic, optoelectronic, optical, electrochemical, environment and biomedical fields. This review provides a comprehensive overview on various physical, chemical and bio-assisted methods largely employed to synthesize and fabricate NPs of varying size, surface characteristics, functionalities and physicochemical behavior. The key applications of nanoparticles have also been discussed.

An operationally simple silver-catalyzed tandem strategy for the synthesis of benzothienopyridines 7a–t and benzofuropyridines 8a–p by the reaction of o-alkynyl aldehyde 4a–t and 5a–p with tert-butylamine 6 under mild reaction conditions is described. The present methodology provides a facile conversion of easily accessible o-alkynyl aldehydes into medicinally useful heterocycles in good to excellent yields under mild and environmentally friendly reaction conditions with excellent regioselectivity. The developed chemistry has been successfully extended for the selective synthesis of C-4 deuterated benzothienopyridines 7u–v and benzofuropyridines 8q–r. The role of the ethanolic proton in the reaction was validated by deuterium-labeling experiments.

The novel, green method is much more milder but more enhanced than earlier reported methods.

Pd(II)-catalyzed α-C(sp3)–H arylation of pyrrolidines, piperidines, azepanes, and N-methylamines with arylboronic acids has been developed for the first time. This transformation is applicable to wide arrays of pyrrolidines and boronic acids, including heteroaromatic boronic acids. A diastereoselective one-pot heterodiarylation of pyrrolidines has also been achieved.

An efficient and green method for the synthesis of the title compounds from erucin and other isothiocyanates is presented.

Base-mediated regio-, stereo-, and chemoselective nucleophilic addition of thiophenols onto bromo-substituted aryl alkynes over S-arylation of aryl halides is described. The regio- and stereochemistry of the products is well supported by spectral studies and X-ray crystallography. Competitive experiments showed that hydroamination is preferred over hydrothiolation. The stereoselectivity, competitive nucleophilic addition, and mechanistic pathway were corroborated by experimental and computational evidence.

A convenient strategy for the synthesis of 3-aryl/alkyl-1,4-benzothiazines has been developed. This reaction proceeds via 1,2-thioacetoxylation of an alkene with silver acetate and acetic acid as an additive, followed by cyclization using TFA. The addition of alkene took place in a regioselective manner, forming exclusively one regioisomer, which was confirmed by a single crystal X-ray study. Various differently substituted alkenes, such as aromatic and aliphatic olefins, were coupled with amino disulfides to form a library of benzothiazine derivatives.

The 1,8-naphthyridine group of compounds have gained special attention of researchers on account of their demonstrating a variety of interesting biological activities. A wide range of biological properties establishes them as potent scaffolds in therapeutic and medicinal research. The broad spectrum of activities primarily includes antimicrobial, antiviral, anticancer, anti-inflammatory, and analgesic activities. 1,8-Naphthyridine derivatives have also exhibited potential applications in neurological disorders such as Alzheimer's disease, multiple sclerosis, and depression. In addition, these synthetic derivatives have been found to possess activities such as anti-osteoporotic (α(v)β(3) antagonists), anti-allergic, antimalarial, gastric antisecretory, bronchodilator, anticonvulsant, anti-hypertensive, platelet aggregation inhibition, anti-oxidant, EGFR inhibition, protein kinase inhibition, ionotropic agent, β-3 antagonist, MDR modulator, adenosine receptor agonist, adrenoceptor antagonist, and pesticide activities. In spite of the widespread application of the 1,8-naphythyridine scaffolds, only a limited number of review articles are available till date. In this review, we attempt to compile and discuss the key data available in the literature for the multiple biological activities of 1,8-naphthyridine derivatives, in a chronological manner. This review compilation (with 199 references) may be helpful in understanding the diverse biological properties of 1,8-naphthyridines and provide insights into their mechanism of action. This may direct future research in the synthesis of new derivatives and exploring this scaffold for other possible biological activities.

The title reaction is assumed to proceed via azide transfer from tosyl azide to dithio esters (I) followed by Wolff-type heterocyclization.

A simple base and ligand free copper catalyzed method for the construction of trifluoromethylated benzoxazines has been developed by using Umemoto's reagent. It involves the oxidative difunctionalization of alkenes through tandem C–O and C–CF3 bond formations. Furthermore, synthesized benzoxazines were selectively converted into trifluoromethylated allylic and (E)-vinylic benzamides by the treatment of KOtBu and CH3Li, respectively.

A novel Pd(II)-catalyzed approach for the direct synthesis of differentially substituted carbazoles from free (NH) indoles via regioselective triple successive oxidative Heck (Fujiwara–Moritani reaction) has been achieved. It is demonstrated that both electron-deficient and electron-rich alkenes could be used successively for the incorporation of two different functional groups into the product. The proposed mechanistic pathway was well supported by isolating the first and second successive oxidative Heck intermediates as well as by trapping with styrene-d3.

The Rh(III)-catalyzed oxidative coupling of 2-aryl-imidazopyridines with internal alkynes via double C–H activation has been described. This approach provides straightforward access to highly functionalized polycyclic imidazopyridines in good to excellent yields.

Chiral ligand 3 was synthesised from inexpensive and readily available (1R,2R)-(+)-1,2-diphenyl-1,2-diaminoethane and tert-butylbromoacetate. In situ generated complex obtained by the reaction of ligand 3 with copper triflate was used as catalyst for asymmetric Henry reaction of trifluoromethyl ketone having different substituents in the aromatic ring with nitromethane at 0 °C in presence of N,N-DIPEA as additive to give nitroaldol products in excellent enantioselectivity (ee upto 99%) with good yield (upto 80%). Ligand 3 with in situ generated complex with copper acetate was also found to be good catalyst for asymmetric nitroaldol reaction of aldehydes (ee up to 80–92%, yield up to 85%) with nitromethane at −5 °C. The DFT calculations performed with B3LYP and M06-2X functionals revealed the role of non-covalent interactions (such as π–π interaction and hydrogen bonding) and the steric factors in the catalyst play important role towards the enhancement of enantioselectivity.

Piperazine is one of the most sought heterocyclics for the development of new drug candidates. This ring can be traced in a number of well established, commercially available drugs. Wide array of pharmacological activities exhibited by piperazine derivatives have made them indispensable anchors for the development of novel therapeutic agents. The review herein highlights the therapeutic significance of piperazine derivatives. Various therapeutically active piperazine derivatives developed by several chemists are reported here.

First time, potentially antimicrobial alkaloids β-sitosterol, esculetin, β-sitosterol-β-D-glucoside, apohyoscyamine, and hyoscyamine are isolated from the methanolic extract of roots of Anisodus luridus.

Whereas the reaction between 2-acylphenols and 4-nitrobenzaldehydes yields 3-benzofuranones, utilisation of 2-nitrobenzaldehyde provides the corresponding flavone product.

Several substituted 2′-amino-biphenyl-2-ols were synthesized. The mild and TM-free double functionalization: nitration and cycloetherification of 2′-amino-biphenyl-2-ols have been achieved for the synthesis of functionalized 4-nitro-dibenzofurans utilizing NaNO2 in TFA and water. Interestingly, nitration of phenol ring was observed along with the dibenzofuran ring formation in the one-pot synthesis. The position of the nitro group in several dibenzofurans is also established by X-ray crystal structure studies. Further functionalization of the obtained 4-nitro-dibenzofurans has been carried into 3-nitro-terphenyl-2-ol, novel benzofuro-indoles, and amino-dibenzofurans. The mechanistic understanding on double functionalization of 2′-amino-biphenyl-2-ols suggests that reaction proceeds by a combination of nitration of the phenol ring followed by Sandmeyer reaction for dibenzofuran ring formation.

Operationally and user-simple a highly efficient one-pot three-component (5 molecules) coupling of α-enolic dithioesters, cysteamine hydrochloride and aldehydes afforded a range of thiazolopyridines in high yields under metal-free and solvent-free conditions. The new domino protocol generated two rings by the concomitant formation of seven multiple bonds (two C–C, three C–N and two C–S) involving a sequence of N,S-acetal formation/double Michael addition/N-cyclization as key steps in a single operation.

It is demonstrated for the first time that aromatic aldehydes can be directly formylated with CO2 as C1 carbon source under base free conditions.

A simple and efficient methoxylation reaction of activated aryl bromides to give the corresponding ethers is presented.

A green and catalyst-free atom-ecomonic straightforward tandem approach for the synthesis of highly functionalized tetrahydroquinazolines by the reaction of 2-aminophenylacrylates with isothiocyanates using water as an environmentally friendly solvent via amidation and concomitant chemoselective Michael-addition is described.

A new and efficient protocol for the synthesis of highly diversified thiazoloquinoline scaffolds by one-pot four-component cascade reaction of α-enolic dithioesters, cysteamine, aldehydes, and cyclic 1,3-diketones is given.

An efficient, waste-free protocol has been developed for the synthesis of amides directly from nonactivated carboxylic acids and amines without any tedious purification. Fatty acids were also converted into corresponding amides by reaction with nonactivated amines. The synthesized amides were cyclized to tetrahydroisoquinolines in good yields.

Compound (IIId) shows better and compounds (IIIe) and (IIIf) show similar activity against Trypanosoma cruzi compared with the reference benznidazole.

Starting from 2-haloanilines, acrylates and arylisothiocyanates or isocyanates medicinally relevant functionalized 2-thioxo or 2-oxotetrahydroquinazolines are prepared.

The synthesis of important drugs such as indoprofen (XIV) and DWP205190 (XI) is achieved from less expensive 2-methylbenzoic acid in two steps, resp., without employing brominating or reducing agent.

β-Arylation in unprotected indoles can be achieved chemo- and regioselectively by employing KOtBu at room temperature in air without using a transition metal catalyst and aryl halide coupling partner.

The method provides access to unsubstituted and 6-substituted 2-imino[1,3]benzothiazines, but is not applicable to the preparation of benzoxazines.

A simple method for preparation of per-O-trimethylsilylated amino sugars with unprotected amines is developed.