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FeF3 catalyzed four component reaction under ultrasound irradiation was explored for the first time to prepare N-substituted 2-aminopyridines in good yields. The methodology involved the use of readily available starting materials and PEG-400 under mild reaction conditions in the presence of air. The one-pot methodology afforded a range of compounds of pharmacological interest indicating its potential in generating a diversity based library of small molecules useful for medicinal chemistry and drug discovery.

A transition metal-free iodine catalyzed synthesis of indolizine derivatives through [3+2] cyclization of 2-pyridylesters and chalcones has been described. The method is efficient to synthesize a variety of substituted indolizines including hetero aromatic indolizines. Mechanistic studies reveal that, the reaction follows the radical pathway.

The ortho-arylation of the title compounds is carried out using aryl boronic acids to afford the target compounds in moderate to good yields and with good functional group tolerance.

An intramolecular cycloaddition of oxonium ylides generated from 3-diazooxindole and a bifunctional substrate i.e. 2-methyl-2-(4-methylpent-3-en-1-yl)-2H-chromene-3-carbaldehyde has been achieved using 5 mol% of Rh2(OAc)4 to produce highly substituted 3,3,5a-trimethyl-3a,5,5a,11b-tetrahydro-3H,4H-spiro[furo[2,3-a]xanthene-2,3′-indolin]-2′-ones in good yields with high diastereoselectivity. This is the first example of the synthesis of biologically relavant polycyclic frameworks from readily accessible precursors.

The pyridine containing decidedly resourceful Pd–N-heterocyclic carbene complex, PEPPSI-SONO-SP2, is being used as a first class catalyst for Suzuki–Miyaura and Sonogashira cross coupling reactions. The catalyst showed a great performance in the consecutive reactions of 4-(4′,6′-dichloro-1,3,5-triazin-2-yl)morpholine with various boronic acids and terminal acetylenes under mild and green conditions (ethanol:water) even in the absence of a blanket of inert atmosphere. Significantly, all the synthesized compounds were found to be new and the catalyst is used for the first time in these reactions. The findings suggest that 0.1 mol% of catalyst is sufficient, recyclable and can be reused for six cycles.

A facile procedure for the copper-mediated oxidative trifluoromethylthiolation of potassium aryl- and heteroaryltrifluoroborates with Ruppert–Prakash reagent and elemental sulfur is presented. Aryl trifluoromethyl thioethers can be prepared in good to moderate yield under mild reaction conditions.

A novel cascade strategy has been developed for the synthesis of tetrahydrospiro[chroman-2,4'-pyran] derivatives by condensation of aldehydes with 2-(5-hydroxy-3-methylenepentyl)phenol. The reaction proceeds smoothly in the presence of BF3·OEt2 under mild conditions in a highly stereoselective manner leading to a single diastereomer. This approach is simple and convenient for the synthesis of pharmacologically relevant spirochroman scaffolds.

An efficient and environmentally benign protocol for the synthesis of a new class of diversely functionalized novel 1 H -indol-3-yl-4 H -chromene-3-carbonitriles has been described through one-pot three-component condensation reaction of 3-(1 H -indol-3-yl)-3-oxopropanenitrile, 5,5-dimethylcyclohexane-1,3-dione, and various aldehydes in the presence of polystyrene-supported p -toluenesulfonic acid (PS/ P TSA) under solvent-free conditions. The present methodology offers several advantages such as short reaction time, simple operational procedure, avoid toxic solvent, high yield of product and endures the substrate diversity. The PS/ P TSA catalyst is readily available in stable form which is fairly inexpensive and can be easily recovered from the reaction medium without appreciable changes for further reuse in the consecutive reaction cycles effectively.

An effective and rapid synthesis of alkylaminophenols using the one-pot three-component Petasis borono–Mannich (PBM) reaction was carried out using protonated trititanate (H2Ti3O7) nanotubes as a heterogeneous solid–acid catalyst. Complimentary to earlier reports, Ti–O based materials with various morphologies, such as fine particles, nanospheres, nanorods, and tubes were explored for their catalytic activity in the PBM reaction. The XRD pattern revealed the layered trititanate structure of nanotubes and nanorods; anatase and biphasic anatase–rutile structures for fine particles and nanospheres, respectively. Surface area analysis and NH3-TPD adsorption results confirmed the larger surface area and high concentration of Bronsted and Lewis acid sites present in H2Ti3O7 nanotubes. The catalytic efficiency for the PBM reaction is observed in the following order: H2Ti3O7 nanotubes > H2Ti3O7 nanorods > TiO2 nanospheres > TiO2 fine particles. The remarkable catalytic performance of H2Ti3O7 nanotubes was ascribed to a sufficient amount of hydroxy groups and high concentration of Bronsted and Lewis acid sites on the tubular surface, which are essential for adsorption and catalytic reactions. The recyclability of H2Ti3O7 catalyst is another emphasis for the proposed methodology. For the first time, we reported novel alkylaminophenols bearing 2-(pyrimidin-2-yl)-2,5-diazabicyclo[2.2.1]-heptane.

Benzoic acids and benzamides are prepared by a novel type of iodine-catalyzed C(CO)-C(alkyl)bond cleavage of aryl/vinyl ketones/phenylacetylenes involving an aerobic oxidation and oxygenation process under air.

The title reaction proceeds under mild conditions and tolerates a wide range of functional groups in both partners.

This facile protocol allows the synthesis of 2-aminoazoles under catalyst-, ligand-, and base-free conditions at room temperature.

The title process is advantageous with regards to operational simplicity and allows the synthesis of novel α-aminophosphonates in short reaction times.

2-Furylcarbinols undergo a smooth aza-Piancatelli rearrangement followed by Friedel–Crafts alkylation with a bifunctional substrate, (1H-pyrrol-1-yl)aniline, in the presence of 10 mol% In(OTf)3 in acetonitrile at room temperature to afford the corresponding hexahydrobenzo[b]cyclopenta[f]pyrrolo[1,2-d][1,4]diazepin-11(4aH)-one scaffolds in good yields. This method offers significant advantages such as high conversions, mild reaction conditions, short reaction times, and high selectivity. The relative stereochemistry of the product was established by nOe studies.

A stereoselective synthesis of decahydrofuro[3,2-d]isochromene derivatives has been achieved by the condensation of 2-cyclohexenylbutane-1,4-diol with aldehydes in the presence of a stochiometric amount of BF3·OEt2 in dichloromethane at −78 °C. Similarly, the condensation of 2-cyclopentenylbutan-1,4-diol with aldehydes provides the corresponding octahydro-2H-cyclopenta[c]furo[2,3-d]pyran derivatives in good yields with high diastereoselectivity. It is an elegant strategy for the quick construction of tricyclic architectures with four contiguous stereogenic centers in a single step. These tricyclic frameworks are the integral part of numerous natural products.

An unusual Pd-catalyzed isocyanide assisted 5-exo-dig reductive cyclization of 1-(2-hydroxyphenyl)-propargyl alcohols is achieved for 2-alkyl/benzyl benzofurans. The reaction features a high substrate scope, insensitivity to air, and excellent product yielding. Further, a direct metal-free C–H functionalization (azidation, alkoxylation, and hydroxylation) and selective oxidative cleavage of thus synthesized 2-benzylfurans are described for azido-, alkoxy-, hydroxyl-, amide-, and tetrazolyl adducts.

In this paper, TiO2 fine particles, TiO2-P25, protonated trititanate (H2Ti3O7) nanorods and nanotubes were used as recyclable solid-acid catalysts for the solvent free synthesis of tertiary α-aminophosphonates through Kabachnik–Fields reaction. Among them, H2Ti3O7 nanotubes showed remarkable catalytic performance and it was due to strong and sufficient Lewis and Bronsted acid sites on a large nanotubular surface. More importantly, for the first time we reported some novel 5,8-dioxa-10-azadispiro[2.0.4.3]undecane bearing tertiary α-aminophosphonates.

A fast, efficient, and green synthesis of pyrimido[4,5-d]pyrimidine derivatives has been achieved via one-pot three-component reaction starting from 6-amino-N,N-dimethyluracil, phenylisothiocyanate or phenylisocyanate, and aromatic aldehydes in the presence of polyethylene glycol-bound sulfonic acid as a catalyst in water as solvent.

A strategy has been devised for the stereoselective synthesis of hexahydroindeno[2,1-c]pyran scaffolds through a domino cyclization of (E)-3,5-diphenylpent-4-en-1-ol with aldehydes using BF3⋅OEt2 at 70 °C. It is an approach for the construction of the indeno[2,1-c]pyran skeleton in a one-pot operation through a cascade cyclization.

An efficient preparation of various highly substituted 2-benzyl furans is developed starting from 2-cinnamyl-1,3-dicarbonyl derivatives.

A novel method is devised for the synthesis of 2,4-disubstituted oxazole derivatives via the coupling of α-diazoketones with amides using copper(II) triflate as the catalyst. The synthetic versatility of this approach is exemplified in the synthesis of an analogue of balsoxin.

A simple and efficient one-pot microwave-assisted click formation of 1-(substituted)-1H-1,2,3-triazol-4-yl)methyl)diphenylphosphineoxide derivatives via Huisgen regioselective [3+2]-cycloaddition of an in situ generated organic azides and diphenyl(prop-2-yn-1-yl)phosphine oxide in highly polar DMSO-H2O medium. This synthetic protocol is mild, requires shorter reaction time, and afforded products in excellent yields with high regioselectivity.

Pyrano[2,3-c]carbazoles which are biologically valuable and synthetically challenging frameworks are synthesized in high yields over five steps from commercially available resorcinol. Palladium-catalyzed arylation remains a key step in this novel strategy. The versatility of this protocol has been demonstrated by the synthesis of naturally occurring alkaloid clauraila C and 7-methoxyglycomaurin. The anti-proliferative activity of these designed compounds (5a, 5f, and 5l) has been evaluated in a cancer cell line (MOLT-4). The molecular docking study revealed that this pyrano[2,3-c]carbazole class of molecules selectively occupies the colchicine binding site of the tubulin-polymer.

Catalytic amounts of DBU·AcOH ionic liquid are used in the neat and environmentally benign protocol for the construction of C—P bonds from nitroalkenes and phosphites.

2-Aryl- and 2-alkenyl-1,3,4-oxadiazoles were efficiently synthesized in high yields by treatment of 1,3,4-oxadiazoles with aryl or alkenyl halides, respectively, in the presence of copper(II) oxide nanoparticles as a catalyst. The reusability of the catalyst is an important advantage in relation to practical applications of this synthesis.

A novel copper-catalyzed aerobic oxidative C(NOH)–C(alkyl) bond cleavage reaction of aryl/aralkyl/vinyl ketones for the synthesis of aromatic/acrylic acids is described. A series of ketones having aryl/aralkyl/vinyl at the one end and methyl to any higher alkyl at the other end can be selectively cleaved and converted into the corresponding acids via oxime intermediates.

A domino cyclization of 3-((3-(2-aminophenyl)prop-2-ynylamino)methyl)but-3-en-1-ol with aldehydes has been accomplished employing 5 mol % of the Ph3PAuCl/AgSbF6/In(OTf)3 system to afford the corresponding octahydrospiro[pyran-4,4′-pyrido[3,4-b]indole] derivatives in good yields with high selectivity. This is the first report on the synthesis of spiro-β-carbolines through a multicatalytic cascade process.

Isochromene derivatives are obtained from enynols and various aldehydes by a sequential Prins/alkynylation/fluorination domino process using stoichiometric amounts of AgSbF6.

An operationally simple and efficient, one-pot, two-step methodology has been developed for the assembly of medicinally important imidazo[1,5-a]quinoxalines. The protocol involves the multicomponent reaction of aryl aldehydes, ortho-N-Boc-phenylenediamines and azidochalcones in the presence of erbium triflate as a Lewis acid catalyst, followed by deprotection–cyclization with 10% trifluoroacetic acid, furnishing the desired compounds in moderate to good yields. By virtue of their convergence, two aromatic rings and four new bonds are generated during the course of this reaction protocol. The structure of one of the compounds was proved by X-ray crystallography.

Diels—Alder reaction between cinnamaldehydes (I) and cyclopentadiene (II) in the presence of (S)-pyrrolidine derivative as catalyst and perchloric acid as additive yields cycloaddition products favouring the endo formation (IV).

A novel “one-pot” aryne transformation is described that affords various 4-quinolone derivatives without recourse to transition-metal catalysis. Arynes react with aza-Morita–Baylis–Hillman (AMBH) adducts through a cascade sequence involving an insertion/cyclization/ene reaction process to afford 4-quinolones in high yields with a broad substrate scope under mild reaction conditions. Essentially, an umpolung of reactivity at the β carbon of α,β-unsaturated ketone has been achieved by an inverse electron demand aryne–ene reaction to provide a C-arylated product.

In this communication, a concise and efficient synthetic route for the synthesis of decarestrictine J in enantioselective way has been described. In this synthesis, Yamaguchi esterification and ring closing metathesis (RCM) for macrocyclic ring formation have been applied as key steps.

A one pot strategy for the synthesis of fused benzoxazino[1,2,3]triazolyl[4,5-c]quinolinone derivatives 4a–4k via the reaction of 5-iodo-4-(prop-2-yn-1-yl)-2H-benzo[b][1,4]oxazin-3(4H)-one (3) with different aryl azides under copper and palladium catalysis in a ligand free condition is achieved. The reaction provided the desired fused triazoles in good to excellent yields. The synthesized derivatives were evaluated for their in vitro cytotoxic activity against MCF-7, A-549 and HeLa cancer cell lines using MTT assay. The cytotoxic activity results revealed that, compound 4d has shown a broad spectrum of activity against MCF-7 and A-549 with IC50 values of 11.18 ± 0.8 and 17.81 ± 0.6 μM, which are comparable to the standard drug, cisplatin. The remaining compounds have shown good to moderate activity against the tested cell lines. Based on the results obtained, a structure activity relationship (SAR) is discussed.

An efficient protocol for the synthesis of highly functionalized furans via intramolecular Wittig reaction has been developed using catalytic amounts of phosphine and triethylamine. Silyl chloride served as the initial promoter to activate the phosphine oxide. Reduction of the activated phosphine oxide by hydrosilane resulted in generation of phosphine, while decomposition of Et3N·HCl resulted in regeneration of base, which mediated formation of phosphorus ylide. Remarkably, the in situ generated byproduct, Et3N·HCl, also catalyzes reduction of phosphine oxide.

An efficient diastereoselective rhodium catalyzed synthesis of indolines possessing two contiguous tetrasubstituted carbon centers has been achieved with good to excellent yields using ortho-vinylanilines and iminocarbenes derived from N-sulfonyl-1,2,3-triazoles. The reaction affords excellent cis-diastereoselectivity through the initial formation of a N-ylide followed by intramolecular trapping with unactivated alkenes via an ene-type reaction with a well-organized transition state, namely intramolecular carbenylative amination of alkenes. The developed transformation was further extended to the successful synthesis of tricyclic compounds, imidazoindolines, through reduction and hypervalent iodine mediated oxidative cyclization.

The novel strategy is based on an oxidative two-step transformation of hydrazine dicarboxylates with aryl iodides.

A wide array of aldehydes undergo smooth cross-coupling with 3-hydroxy-3-(4-hydroxybut-1-en-2-yl)-1-methylindolin-2-one in the presence of 10 mol% BF3·OEt2 at 0 °C in dichloromethane to afford the corresponding 2,3,5,6-tetrahydro-1′H-spiro[pyran-4,4′-quinoline]-2′,3′-dione derivatives in good yields with excellent diastereoselectivity. This is the first report on the synthesis of tetrahydro-1′H-spiro[pyran-4,4′-quinoline]-2′,3′-dione scaffolds through a cascade of Prins/pinacol reactions.

A facile protocol for the three-component condensation of o-hydroxy benzaldehydes, boronic acids, and amines to form the title products in high yields is presented.