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An efficient synthetic protocol of pyrroles and isoquinolines through NaN3/NH4Cl promoted intramolecular aza-annulation of formyl group with suitable alkenes or alkynes is described in high yield and regioselectivities. The metal free exo-trig and endo-dig aza-cyclisation has been extended for the synthesis of bicyclic or tricyclic pyrroles along with environment sensitive fluorescent isoquinoline derivatives. Reactions occur in excellent yields, broad scope and high tolerance of functional groups. The synthetic utility of this methodology was demonstrated in the short synthesis of the core structure of lamellarin Q.

A method for the palladium-catalyzed arylation of α,β-unsaturated valerolactams is reported. This new protocol provides arylation products in yields up to 95% and is applicable to a wide array of aryl and heteroaryl bromides. The optimization, scope and limitations are described.

NH-1,2,3-Triazole moieties are a part of the design of various biologically active compounds, pharmaceutical agents and functional materials. Unfortunately, the applications of this heterocycle are still underexplored due to the lack of a general synthetic protocol. Here we outline a novel, general and facile metal-free pathway that enables the direct synthesis of these heterocycles by combining readily accessible and abundant precursors such as enolizable ketones and NH4OAc with high levels of regioselectivity via an organocascade process. The developed chemistry has been successfully applied to the synthesis of several structurally diverse products, pharmaceutical agents and supramolecular receptors.

A unique copper-catalyzed binucleophilic switching of 2-aminopyridine has been developed for the regioselective synthesis of 2- and 3-iodoimidazo[1,2-a]pyridines using alkenes/alkynes as coupling partners in the presence of molecular iodine under aerobic reaction conditions. This method was also applied to the synthesis of 2-iodo-3-phenylbenzo[d]imidazo[2,1-b]thiazoles. This protocol offers an easy route towards the synthesis of 2,3-diarylimidazo[1,2-a]pyridines.

Azo imidazoheterocycles are prepared with broad substrate scope by the title coupling in good yields.

We report herein a Pd(II)-catalyzed Heck-type coupling between arene carboxylic acids and alkenes at room temperature. Mechanistically, the reaction proceeds in two distinct pathways where electron-rich substrates undergo a palladium(II)-catalyzed decarboxylation and electron-deficient substrates proceed through silver(I)-assisted decarboxylation. Dimethyl sulfoxide (DMSO) or sulfide ligands have positive and negative roles in the reaction outcome, respectively. The present protocol is combined for the peptide modification under mild reaction conditions.

A large variety of synthetic methods have been developed for the synthesis of functionalized aliphatic amines because of their broad spectrum of application. Metallic reagents/catalysts and/or toxic oxidants are involved in most of the cases. Direct CH functionalization of aliphatic amines via their classical condensation reactions with suitable carbonyl compounds is advantageous because this method avoids hazardous metallic reagents, toxic oxidants and pre-activation/pre-functionalization step(s). In this account, the concept of direct CH functionalization of aliphatic amines based on the classical condensation-isomerization-addition (CIA) strategy followed by recent contributions from our ongoing research in the field along with relevant examples from other groups are described. Successes in stereo- and regioselective CC and CO bond formation via direct α- as well as β-C(sp(3) )-H functionalization are discussed.

A simple and facile approach for the synthesis of various structurally different tricyclic bent oxepine frameworks from a readily accessible precursor has been introduced. The synthesis of substituted oxepine derivative involved Pd(0)-catalyzed Heck reaction. This methodology enriches the literature for the large ring formation.

A series of C-cinnamoyl glycosides has been synthesized in good yield by the BF3·OEt2 catalyzed aldol condensation of C-glycosylated acetone derivative with a variety of aromatic aldehydes. The synthesized compounds were evaluated for their potential as anti-filarial agents against bovine filarial parasite Setaria cervi and human filariid Wuchereria bancrofti using a number of biological assays such as relative movability (RM) assessment and MTT reduction assay. Among twenty seven test compounds six compounds were found active in terms of MIC, IC50 and LC50 values. Further biological studies were carried out using three lead compounds because of their significantly low MIC values and IC50 values compared to the standard anti-filarial drug Ivermectin. In addition, structure activity relationship study of the test compounds has been carried out using 3D-QSAR analysis.

A range of tetracyclic dibenzofuran derivatives bearing a variety of functional groups was readily synthesized via a two-stage domino strategy starting from propargyl ethers of 2-halo phenol derivatives. The first stage in the strategy involves Pd(0)-catalyzed domino intramolecular carbopalladation/Suzuki coupling via 5-exo-dig cyclization onto the alkyne, leading to 3-methylene-2,3-dihydrobenzofuran derivatives. In the second stage of the domino strategy, an iron(III)-catalyzed cycloisomerization and aromatization reaction produces tetracyclic benzofuran derivatives. This two-step sequence provides efficient access to diversely substituted polycyclic dibenzofuran derivatives in high yields and in an atom-efficient and environmentally friendly manner. Moreover, this strategy was also successfully used for the synthesis of a naturally occurring tetracyclic dibenzofuran, β-brazan.

An unprecedented selective preparation of 1,5-disubstituted 1,2,3-triazoles from readily available primary amines, enolizable ketones and 4-nitrophenyl azide as a renewable source of dinitrogen is developed.

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 general and direct strategy for the synthesis of chiral spiro-aziridine oxindoles has been developed via an aza-Corey–Chaykovsky reaction of isatin-derived N-tert-butanesulfinyl ketimines with excellent selectivity (dr = 98:2 to >99:1). The method is explored for the synthesis of chiral 3-substituted spiro-aziridine oxindoles with high (2S,3S)-selectivity over (2S,3R).

A practical method for the ortho C—H hydroxylation of benzamides with inexpensive copper(II) acetate monohydrate and a pyridine ligand is presented.

Aryl or vinyl substituted bis-propargyl ethers upon base treatment generally form phthalans via the Garratt–Braverman (GB) cyclization pathway. In a major departure from this usual route, several aryl/vinyl bis-propargyl ethers with one of the acetylenic arms ending up with 2-tetrahydropyranyloxy methyl or ethoxy methyl have been shown to follow the alternative intramolecular 1,5-H shift pathway upon base treatment. The reaction has led to the formation of synthetically as well as biologically important 3,4-disubstituted furan derivatives in good yields. The initially formed E isomer in solution (CDCl3) slowly isomerizes to the Z isomer, indicating greater stability of the latter. The factors affecting the interplay between the 1,5-H shift and GB rearrangement have also been evaluated, and the results are supported by DFT-based computational study.

Dibromobenzoisofuranone 12, synthesized in six steps, was regiospecifically annulated with 5-substituted cyclohexenones 13/36 in the presence of LiOt-Bu to give brominated anthraquinones 14/38 in good yields. Darzens condensation of 30 was shown to give chain-elongated anthraquinone 32. Alkaline hydrolysis of 38 furnished 39 representing desulfoproisocrinin F.

A palladium-catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2-arylindoles and diaryliodonium salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected "through-space" 1,4-palladium migration to the 2-aryl moiety, by remote C-H bond activation followed by C-H arylation with diaryliodonium salt, and an unprecedented 1,2-aryl shift take place. Finally, an intramolecular cross-dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C-H bond activation one C-C bond cleavage, and the simultaneous construction of three new C-C bonds in a single operation.

The new cascade title reaction between 3-cyano phthalides and α-substituted acrylates is elaborated.

Optically active 5-aryl 2,5-disubstituted pyrrolidines are the principal structural moiety of many bioactive compounds including natural products and catalysts for asymmetric synthesis. A highly regio- and diastereoselective and enantiospecific method for direct C-H arylation of aliphatic amine has been developed. Structurally diverse enantiopure arylated pyrrolidines were synthesized from commercially available starting materials, through a single-step three-component reaction under metal- and oxidant-free conditions. Furthermore, the complex analogous structure of CCK antagonist RP 66803 and angiotensin-converting enzyme inhibitors was easily constructed using the synthesized arylated pyrrolidine derivative. Detailed theoretical calculations (M06-2X/TZVPP/SMD//M06-2X/6-31+G(d,p) level) were also carried to investigate the mechanism and high level of stereocontrol involved in this direct sp(3) C-H arylation reaction. Preference for a given regio- and stereoselectivity in the arylated product can be explained through elucidation of the mechanism for dehydration, generating azomethine ylide, and for the final re-aromatization step. The calculated energies reveals that the re-aromatization step is essentially rate determining, accompanying an activation barrier of Δ(≠) G=25.6 kcal mol(-1) .

The new title compound is synthesized in 95% yield from mixtures of Eu, Ir, excess In as an active metal flux, and Si to nucleate crystal growth (alumina crucible, 1273 K for 6 h, followed by annealing at 1123 K for 72 h).

Based on the bottom-up chemistry techniques, the size, shape, and composition controlled synthesis of nanoparticles can now be achieved uniformly, which is of great importance to the nanoscience community as well as in modern catalysis research. The low-temperature solution-phase synthesis approach represents one of the most attractive strategies and has been utilized to synthesize nanoscale metals, alloys and intermetallics, including a number of new metastable phases. This perspective will highlight the solution-based nanoparticle synthesis techniques, a low-temperature platform, for the synthesis of size and shape-tunable nanoscale transition metals, alloys, and intermetallics from the literature, keeping a focus on the utility of these nanomaterials in understanding the catalysis. For each solution-based nanoparticle synthesis technique, a comprehensive overview has been given for the reported nanoscale metals, alloys, and intermetallics, followed by critical comments. Finally, their enhanced catalytic activity and durability as novel catalysts have been discussed towards several hydrogenation/dehydrogenation reactions and also for different inorganic to organic reactions. Hence, the captivating advantages of this controllable low-temperature solution chemistry approach have several important implications and together with them this approach provides a promising route to the development of next-generation nanostructured metals, alloys, and intermetallics since they possess fascinating properties as well as outstanding catalytic activity.

A simple and convenient approach is developed for the selective synthesis of indoles and benzofurans by isomerization of methyleneindolines and -dihydrobenzofurans.

A simple protocol for the synthesis of dihydrobenzothiazines through regio- and stereoselective S(N)2-type ring opening of N-tosylaziridines with sulfur nucleophiles followed by copper-powder-mediated intramolecular C-N cyclization in excellent yields (up to 95%) with high diastereo- and enantioselectivity (up to >99%) is reported.

A simple, efficient, and practical method for the phenylselenylation of imidazo[1,2-a]pyridines via electrophilic substitution employing readily available phenylselenium bromide has been developed in aqueous media at room temperature. A library of 3-phenylselenylimidazo[1,2-a]pyridines has been synthesized employing this methodology with high yields. The present protocol is also applicable for the phenylselenylation of imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole.

A metal-free method for direct β-C(sp3)–H functionalization of aliphatic amine was developed. The method is based on a reaction that yields enamine directly from the corresponding aliphatic amine, which otherwise requires the aid of metallic reagent and/or external oxidant. The reaction is operationally simple, general, and highly efficient in functionalizing both cyclic and acyclic amines. Structurally diverse unsaturated imines were obtained from N-heterocycles, while acyclic amines provided 2-alkyl cinnamaldehyde and benzopyran derivatives with excellent E/Z-selectivity.

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.

The chiral cyclometalated π-allyliridium ortho-C,O-benzoate complex (R)-Ir-VIb derived from [Ir(cod)Cl]2, allyl acetate, 4-cyano-3-nitro-benzoic acid, and (R)-MeO-BIPHEP catalyzes the coupling of N-(p-nitrophenylsulfonyl) protected vinyl aziridine 3a with primary alcohols 1a-1l to furnish branched products of C-C bond formation 4a-4l with good levels of anti-diastereo- and enantioselectivity. In the presence of 2-propanol, but under otherwise identical conditions, vinyl aziridine 3a and aldehydes 2a-2l engage in reductive coupling to furnish an equivalent set of adducts 4a-4l with roughly equivalent levels of anti-diastereo- and enantioselectivity. Using enantiomeric iridium catalysts, vinyl aziridine 3a reacts with unprotected chiral 1,3-diols 1m-1o in a site-selective manner to deliver the diastereomeric products of C-allylation syn-4m, -4n, -4o and anti-4m, -4n, -4o, respectively, with good isolated yields and excellent levels of catalyst-directed diastereoselectivity. These adducts were directly converted to the diastereomeric 2,4,5-trisubstituted piperidines syn-5m, -5n, -5o and anti-5m, -5n, -5o.

A simple and practical method has been developed for the regioselective nitrosylation of imidazopyridines via C(sp2)–H bond functionalization using tert-butyl nitrite under mild reaction conditions in a short time. A library of 3-nitrosoimidazopyridines with broad functionalities was synthesized in near quantitative yields. The present protocol is also applicable to imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole.

Triene (III) prepared by coupling of the (S)-alcohol (I) with phosphate (II) undergoes ring-closing metathesis to produce the bicyclic phosphate (IV) having a conformationally fixed P-stereogenic center.

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.

The development of processes that streamline the synthesis of complex, functionalized carbocycles and heterocycles remains a hotly pursued topic because their scaffolds are present in a range of bioactive molecules and electronic materials. Although the Nazarov reaction has emerged to be useful in the synthesis of carbocycles and heterocycles, using an electrocyclization to trigger a migration remains underdeveloped. By constructing several bonds in one operation, domino reaction sequences are particularly effective at improving the efficiency of synthesis. The use of transition metal catalysts has the potential to render these processes stereoselective. This review examines the use of electrocyclization–[1,2] migrations to construct molecules and is organized by the type of ring constructed and the order of the two steps in this process.

The combination of Mo(CO)6 and 10 mol % of palladium acetate catalyzes the transformation of 2-nitroarenes to 3H-indoles through a tandem cyclization-[1,2] shift reaction of in situ generated nitrosoarenes. Mo(CO)6 appears to have dual roles in this transformation: generate CO and promote C–N bond formation to increase the yield of the N-heterocycle product.

A novel silica-tethered ruthenium complex (RPOS) is prepared and successfully applied as a photocatalyst for the oxidative aromatization of Hantzsch esters [→ (III), (IV)], the reductive dehalogenation of halides (V) and (VII), and the halogenation of alcohols (IX).

Exposure of trisubstituted styryl azides (I), (IV), (VI), and (VIII) to Rh2(II)-carboxylate catalyst triggers a tandem 4π-electron-5-atom electrocyclization-migration reaction.

Described herein is the generation and use of iodohexahydropyridoindolines and their free radical atom transfer reactions with aryl acetylenes to generate quaternary substituted pyridoindolones.

A mild protocol for the selective β- and α-arylation of allylic and cinnamyl alcohols using aryldiazonium salts is reported.

Ferrocenyl phosphane–carbene ligands catalyze domino reactions composed of conjugate addition of Grignard reagents to α,β-unsaturated lactone followed by enolate trapping with activated alkenes. The corresponding α,β-disubstituted lactones were obtained in medium yields, but with high diastereomeric and enantiomeric purities up to 98:2 er.

The role of Ti, Fe, and Mn on H diffusion in MgH2 is studied by DFT calculations using the PW91 generalized gradient functional on a 71 atom 2 x 2 x 3 supercell of rutile-type MgH2 in which one Mg host atom is replaced by the dopant.

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.

An iron-catalyzed efficient synthesis of substituted phenanthrenes through tandem intramolecular C–C/C–O bond formations/aromatization of 2′-alkynyl-biphenyl-2-carbinols is reported. This method provides a novel, highly efficient, and straightforward route to 9,10-substituted phenanthrene in good to excellent yields. The present strategy involves tandem Fe(OTf)3-catalyzed generation of benzylic carbocation, 6-exo-dig cyclization of alkyne, carbon–oxygen bond formation, and aromatization steps in one pot.

A transition-metal-free oxidative cross-coupling of two different alcohols is achieved using Oxone as oxidant and a mixture of TEMPO and Bu4NBr as catalysts.

The flexible and versatile strategy offers access to biologically and pharmaceutically relevant tetracyclic indole, benzofuran and benzothiophene derivatives bearing aryl, hetaryl and alkyl substituent on the azulene ring.

The η phase in the Au-Cd binary system is prepared from the elements in stoichiometric ratio (evacuated silica tubes, 1.

The remarkably efficient synthesis of biologically relevant diazepines, diazocines, and diazonines is also performed using conventional heating instead of microwave irradiation with virtually identical product yields after slightly longer reaction times.

Metal, oxidant and other additive-free novel methods for direct C–H aryloxylation of aliphatic amines are developed. In the presence of excess amine, the course of the reaction was diverted, producing various arylmethylamines via hydride-free formal reductive amination. Involvement of a quinone methide intermediate was revealed from mechanistic studies.