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An efficient and practical method for the in situ generation of palladium nanoparticles was successfully established in a water extract of pomelo peel ash. The produced palladium nanoparticles were characterized by energy-dispersive X-ray spectroscopy elemental mapping, field emission scanning electron microscopy, high-resolution transmission electron microscope, X-ray powder diffraction, and showed high catalytic activity for selective C-2 arylation of indoles. A series of 2-arylindoles were smoothly installed in moderate to good yields through the direct palladium-catalyzed cross-coupling reactions of indoles and iodoarenes without external ligand, base, oxidant, and preinstallation directing group. [ABSTRACT FROM AUTHOR] more...

Herein, we describe two types of C5 functionalization reactions of chromones with allyl alcohols. Diverse 5-substituted chromones can be produced by modulating the catalysts in these reactions: Rh(III) results in the formation of 5-alkylated chromones, and Ru(II) furnishes 5-alkenylated products. We also achieve further functionalizations of these 5-substituted chromones, which demonstrates the superiority of this method. Notable features of these new methods include readily available precursors, tunable reactivity, exclusive C5-selectivity, and easy derivatization of products. [ABSTRACT FROM AUTHOR] more...

We have developed a regioselective hydroarylative coupling of indolines with internal alkynes by the activation of C-H bond using inexpensive Ru(II)-catalyst. This redox-neutral, atomeconomical, and scalable C-H functionalization has been accomplished using easily removable weakly coordinating directing group. Diverse unsymmetrically substituted alkynes appended with pharmacologically important heterocycles were coupled with various indolines and 1,2,3,4-tetrahydroquinolines to furnish the corresponding trisubstituted alkenes with very high regioselectivity. The application of the method has been demonstrated with a number of alkyne-containing drug molecules, natural products, carbohydrates, amino acids, steroids, and other heterocycles. Preliminary mechanistic interrogation revealed that the C-H activation proceeds through baseassisted internal electrophilic-type substitution process. [ABSTRACT FROM AUTHOR] more...

A simple method for the direct Pd(OAc)2‐catalyzed oxidative arylation of inactivated 1H‐indazole derivatives with simple arenes is reported. This method exhibits good reaction efficiency and good functional‐group tolerance. Using the developed method, 28 arylated products were prepared in yields up to 80 %. [ABSTRACT FROM AUTHOR] more...

A novel synthetic route for the construction of (E)‐3‐alkylideneindolin‐2‐ones through iron‐catalyzed aerobic oxidative condensation of oxindoles with benzylamines has been developed. This oxidative reaction involves a sequence of C–H activation, amine self‐condensation, nucleophilic addition, and C–C double bond formation. The synthetic importance of this protocol has been demonstrated by preparing tyrosine kinase inhibitors, anticonvulsant and antitumor agents, and other valuable 3‐alkylideneindolin‐2‐one derivatives. Key intermediates are isolated and a plausible mechanistic pathway for the reaction has been discussed. [ABSTRACT FROM AUTHOR] more...

An efficient, one‐pot copper catalyzed 3‐fold C–N bond‐coupling strategy leading to pharmaceutically relevant benzimidazole heterocycles is reported. Our strategy involves a copper catalyzed intramolecular C–N coupling of N,N'‐bis(2‐bromophenyl)formamidine to provide 1‐(2‐bromophenyl)‐1H‐benzimidazole which upon intermolecular coupling with 2‐amino pyridines and a cascade sp2 C–H amination furnished a range of benzimidazo[1,2‐a]benzimidazoles. [ABSTRACT FROM AUTHOR] more...

Desymmetrization of meso compounds is well recognized as a powerful method for delivering biologically relevant molecular skeletons in a few synthetic steps. Heterobicyclic olefins are a class of meso compounds which exhibit exceptional reactivity due to their high ring strain originating from the unfavorable bond angles and eclipsing interactions. Extensive research was carried out towards the synthetic transformations of oxa‐, aza‐, and diazanorbornenes/norbornadienes for the synthesis of a wide variety of carbocycles and heterocycles in a single step, most importantly in a stereo‐ and chemo‐selective manner. This review summarizes the relevant aspects of diazanorbornene reactivity which will inspire the synthetic community for exploiting these highly strained bicyclic systems for the creation of extensive libraries of novel structurally and biologically interesting molecules. The review is divided into several sections based on the type of reactions that diazanorbornenes are subjected to. [ABSTRACT FROM AUTHOR] more...

Metal complexes containing cyclopentadienyl (Cp) ligands are versatile and robust catalysts widely applied in organic synthesis. During the last two decades chiral Cpx complexes have been applied in a variety of enantioselective transformations. Often associated with Group 9 metals (Co, Rh, Ir), chiral Cpx ligands have also been used in combination with early transition‐metals and rare‐earth elements. In this minireview asymmetric reactions that have been successfully steered with chiral Cpx ligand metal complexes are discussed according to the metal coordinated. Several ligand designs have successfully been used in a diverse array of reactions, in particular C–H functionalisation, with binaphthyl‐derived ligands leading this field. Challenges with these ligands derive from the need for their multi‐step synthesis, and recently new ligands were designed, which can be accessed in shorter sequences from readily available starting materials. [ABSTRACT FROM AUTHOR] more...

Five‐membered heteroarenes constitute ubiquitous moieties in bioactive compounds and materials. It is thus not surprising that a direct and selective access to multiply substituted heteroarenes is considered as a highly attractive synthetic target. The direct olefination of such substrates, also known as cross‐dehydrogenative coupling has raised significant interest in this context. However, achieving site‐selectivity remains challenging with some substitution patterns such as 3‐substituted heteroarenes. Suitable catalyst systems and reaction conditions have to be identified, which enable the differentiation between the competing C2‐ and C5‐position. Over the last few years, substantial progress has been made to overcome this selectivity challenge mainly based on the use of novel ligand systems, which will be described herein. [ABSTRACT FROM AUTHOR] more...

A new chiral cyclopentadiene CpmyrH was synthesized from the natural terpene (R)‐myrtenal in 5 steps and about 40 % total yield. The key step was the reaction of vinyl‐dibromocyclopropane derivative with MeLi which provided the diene CpmyrH via Skattebøl rearrangement. The reaction of CpmyrH with [(cod)Rh(OAc)]2 gave the rhodium(I) complex (Cpmyr)Rh(cod) and subsequent oxidation with halogens X2 gave the rhodium(III) complexes [(Cpmyr)RhX2]2 (X = Br, I). Complex (Cpmyr)Rh(cod) in combination with benzoyl peroxide catalyzed the C–H activation of O‐pivaloyl‐phenylhydroxamic acid and its subsequent annulation with alkenes giving dihydroisoquinolones with high yield (70–90 %) but moderate enantioselectivity (16–36 % ee). [ABSTRACT FROM AUTHOR] more...

A facile C(sp2)–H activation of aldehyde under visible‐light conditions using Cu@g‐C3N4 as photocatalyst and water as solvent is reported. The envisaged method involves photocatalytic intermolecular Stetter reaction using differently substituted aldehydes and acrylonitrile to produce various γ‐keto nitriles in good to excellent yield (80–95 %) and 4–10 h at r.t. Operational simplicity, ambient reaction conditions, visible‐light condition, and application of the Cu@g‐C3N4 as photocatalyst make the envisaged protocol an efficient and highly green alternative to the existing methods for synthesis of γ‐keto nitriles. [ABSTRACT FROM AUTHOR] more...

An efficient one‐pot strategy evolved in the synthesis of (E)‐4‐benzylidenylacridin‐1(2H)‐ones, (4 or 9) (E)‐2‐styryl quinoline‐3‐carboxamides (5 or 10) by sequential Suzuki–Miyaura coupling‐dehydrogenative Friedländer‐sp3 C–H activation. The 2‐amino‐5‐chloro benzhydrol 1, aromatic alcohol 2 or 6 ketones 3 or 3', and phenylboronic acid 7 underwent a smooth reaction in a basic deep eutectic solvent consisting of K2CO3 and ethylene glycol (DES‐1,1:1). DES‐1 could enable the Pd‐catalyzed Suzuki coupling reaction of 6, as well as the rapid oxidation of primary, secondary, and Suzuki coupled primary alcohols (2, 1, and 8) in the presence of an iridium catalyst and 1,10‐phenanthroline. The acidic DES‐2 (dimethyl urea/tartaric acid, 7:3) assists the Friedländer annulation and subsequent sp3‐C–H functionalization resulting in (E)‐4‐benzylidenylacridin‐1(2H)‐ones (4 or 9) and (E)‐2‐styryl quinoline‐3‐carboxamides (5 or 10). [ABSTRACT FROM AUTHOR] more...

A highly efficient and practical procedure for chemo‐ and regioselective synthesis of ortho‐diacylbenzenes through Pd‐catalyzed oxidative C–H bond activation has been developed. Using this method, a variety of ortho‐diacylbenzenes were prepared in moderate to good yields, by direct acylation of diazines with toluene derivatives as acylation source. Ortho‐diacylbenzenes may be used as precursors in synthesis of pharmaceuticals and agrochemicals. [ABSTRACT FROM AUTHOR] more...

The late‐stage C–H diversification methodology was applied to the preparation of arylated Diflufenican derivatives. Using a palladium catalyst associated with potassium pivalate, a regioselective arylation of the C–H bond flanked by the two fluorine atoms was observed. The reaction tolerated a wide range of useful functional groups on the aryl bromide. Conversely, the use of a ruthenium catalyst allowed to arylate the trifluoromethylbenzene ring of Diflufenican. To the best of our knowledge, these synthetic schemes are the first ones allowing the preparation of such arylated Diflufenican derivatives. [ABSTRACT FROM AUTHOR] more...

With alkyl carbazates as the green ester source, a novel palladium‐catalyzed oxidative free radical carbonylative transformation of the C–H bond on aromatic rings to produce esters has been developed. Good yields of the corresponding products have been obtained with wide functional group tolerance and excellent regioselectivity. A variety of alkyl carbazates are found to be suitable reactants for the ortho‐alkoxycarbonylation on the aromatic ring. [ABSTRACT FROM AUTHOR] more...

Herein, we demonstrate a [RhCp*Cl2]2 catalyzed synthesis of isoindolo[2,1‐b]isoquinolin‐5(7H)‐one derivatives from N‐(pivaloyloxy)benzamides and p‐quinone methides under redox neutral conditions. p‐Quinone methide derivatives were engaged for the first time as precursors in C–H activation reactions and the cascade sequence consists of Rh(III)‐catalyzed C–H activation, alkyne insertion followed by an intramolecular 1,6‐conjugate addition. This novel tandem reaction strategy offers a rapid and straightforward access to complex fused isoquinolinone derivatives in an efficient manner. [ABSTRACT FROM AUTHOR] more...

A simple procedure for the copper‐catalyzed synthesis of 3‐(N‐heteroaryl)acrylonitriles was developed. Using a combination of Lewis and Brønsted acids, this one‐pot procedure undergoes via a radical conjugated addition and dehydration processes, without isolation of any intermediate, affording the acrylonitriles. This diastereoselective approach allowed the synthesis of a broad scope of quinazoline derivatives (22 examples) with moderate to good yields and good functional‐group tolerance and could be extended to other N‐heterocyles such as quinolines and isoquinolines. Based on control experiments, a mechanistic proposal for this new transformation is also presented. [ABSTRACT FROM AUTHOR] more...

The rhodium (III)‐catalyzed annulation of 3‐Aryl‐2H‐Benzo[b][1,4]oxazines with alkynes via C–H activation has been developed. This reaction afforded a series of spiro indenyl benzoxazine in high yields under mild reaction condition with good functional group tolerance. [ABSTRACT FROM AUTHOR] more...

The PdII‐catalyzed C‐2 acylation of pyrrole with aldehydes in the presence of TBHP as oxidant has been studied for the synthesis of di(hetero)aryl ketones. The use of 2‐pyrimidine as directing group leads to 2‐acylpyrroles in moderate to good yields, although 2,5‐diacylpyrroles are obtained as by products. This side‐reaction could be avoided using 3‐methy‐2‐pyridine as directing group, obtaining selectively 2‐acylpyrroles. The reaction has been extended to a series of aromatic and heteroaromatic aldehydes, obtaining the best results with electron rich aromatic aldehydes. The methodology has been applied in the synthesis of pyrrolomycin alkaloid Celastramycin analogues and for an improved synthesis of Tolmetin, a nonsteroidal anti‐inflammatory drug. [ABSTRACT FROM AUTHOR] more...

Highly facile approach of chemoselective alkylation of α-oxo compounds such as α-keto amides, α-keto esters, isatins, and cyclic-α-diketones is developed through C(sp³)-H functionalization of 2-methyl quinolines under solvent and catalyst-free conditions. Further, we complemented the efficacy of this green synthetic protocol by demonstrating the broad substrate diversity, gram-scale synthesis, and new synthetic transformations of the obtained products. [ABSTRACT FROM AUTHOR] more...

Among a series of iron salts, iron triflates revealed as highly active catalysts for the oxidation of cyclohexane by tert‐butyl hydroperoxide into cyclohexanol and cyclohexanone with initial turnover frequencies higher than 10,000 h–1. The structure of the iron complexes under the reaction conditions was studied by combining electron paramagnetic resonance (EPR) spectroscopy and DFT calculations. The coordination of the catalytic iron center readily evolved in the presence of the reaction products, leading ultimately to its deactivation. Iron and organic superoxo intermediates were identified as plausible active species allowing to rationalize the high activity of iron ligated by highly delocalized counter‐anions. [ABSTRACT FROM AUTHOR] more...

This review covers our recent contribution on the synthesis of extended polyconjugated compounds, such as conjugated polymers and small molecules. The synthetic strategies developed in our research group are mainly based on palladium‐catalyzed cross‐coupling reactions involving a variety of organometallic intermediates as well as on direct arylation reactions via C–H functionalization. This report is organized according to the synthetic methods used (coupling of unsaturated organosilanes, Suzuki–Miyaura cross‐coupling, Stille cross‐coupling, direct arylation) and the typologies of the structures synthesized (polymers, small molecules). [ABSTRACT FROM AUTHOR] more...

Fully substituted triazoles are synthesized by a sustainable direct arylation reaction performed under solvent‐free conditions and in the presence of a recyclable Pd/C heterogeneous catalyst. Exclusion of air as well as anhydrous conditions are not required, enabling a convenient synthesis of 1,4,5‐trisubstituted 1,2,3‐triazoles and 1,2,3‐triazole‐fused isoindolines starting from 1,4‐disubstituted 1,2,3‐triazoles, easily prepared via click chemistry, and functionalized aryl iodides. [ABSTRACT FROM AUTHOR] more...

Rh‐catalyzed meta‐C–H activation is always a great challenge, especially for selectivity control. Herein, Rh(III)‐catalyzed meta‐C–H alkenylation with alkynes was investigated to elucidate the mechanism details and clarify the origin of regio‐ and mono/di‐selectivity by using DFT methods. Calculation results indicate that C–H activation is the selectivity‐determining step for the protocol. More mechanistic studies on substituted substrates further support our conclusions. For meta‐C–H alkenylation, protonation is most likely the rate‐determining step. The calculations of two possible protonation pathways show that the protonation route after the macrocyclic opening and release of the ring strain is kinetically favorable. Mechanism and BDE calculations also show that the meta‐H exhibits the smallest C–H BDE and C–H activation reaction barrier, leading to the good meta‐selectivity. [ABSTRACT FROM AUTHOR] more...

Fluoroarenes can be selectively deuterated by H/D exchange with common deuterated solvents in the presence of a catalytic amount of an alkali metal carbonate or, for the less acidic arenes, stoichiometric quantities of potassium phosphate. This is a sustainable method that does not need transition metal catalysis or the multistep synthesis of a main‐group organometallics. This exchange needs to be taken into account when using H/D scrambling as a mechanistic probe in reactions involving fluoroarenes. [ABSTRACT FROM AUTHOR] more...

The first example of direct C–H bond monofluoroalkylation with 1‐fluoro‐1‐haloalkanes with no adjacent functional groups and with β‐hydrogens has been developed. This transformation offers a straightforward route for the synthesis of a series of monofluoroalkylated benzoxazoles. [ABSTRACT FROM AUTHOR] more...

A stepwise non‐enzymatic conversion of the natural amino acid L‐tyrosine into physiologically relevant intermediates L‐DOPA, dopaquinone and dopachrome has been demonstrated in aqueous solution under ambient conditions. The photocatalytic redox process applied involves controlled activation of molecular oxygen forming water and hydrogen peroxide as further reaction products. Substrate conversion can be switched on and off conveniently by regulating the degree of visible‐light or sunlight exposure of an immobilized multielectron transfer sensitizer, which is very easy to apply and can be separated again from the supernatant reaction medium. Quantitative analysis of the six‐electron redox conversion of L‐tyrosine catalyzed by the artificial oxidoreductase enzyme system reveals a remarkable degree of abiotic phenolase activity which nearly approaches the benchmark value of the native metalloenzyme tyrosinase under substrate saturation conditions. [ABSTRACT FROM AUTHOR] more...

A ruthenium‐catalyzed meta‐selective CAr–H bond difluoroalkylation of 2‐phenoxypyridine using 2‐bromo‐2,2‐difluoroacetate has been developed. Mechanistic studies indicated that this difluoroalkylation might involve a radical process. Furthermore, a new method is reported for the synthesis of 2‐(meta‐difluoroalkylphenoxy)pyridine derivatives, which are present in many pharmaceuticals and other functional compounds. [ABSTRACT FROM AUTHOR] more...

The Co(II)Cl2·6H2O catalyzed C–H activation/direct arylation of imidazo[1,2‐a]pyridine with aryl/heteroaryl iodide is reported. The cost effective, ligand and additive free protocol using KOAc successfully afforded 3‐arylimidazo[1,2‐a]pyridines in good yields. Imidazo[1,2‐a]pyridines with electron withdrawing and electron donating substituents with various aryl iodides are well tolerated. The reaction is performed in a Screw‐top V‐Vial® to expedite the synthesis. The antibacterial 3‐naphthyl imidazo[1,2‐a]pyridine is smoothly prepared using this protocol. [ABSTRACT FROM AUTHOR] more...

A new application of hydroxylamine‐O‐sulfonic acid (HOSA) has been discovered whereby aromatic ketones react with HOSA and alkynes to form isoquinolines in the presence of a RhIII catalyst. This C–H/N–O annulation methodology gives excellent yields even without any silver additive, acid/base or metal oxidant. This is the first report wherein a directing group is simultaneously forming in situ, acting as acid additive, and also as an internal oxidant. [ABSTRACT FROM AUTHOR] more...

The 2‐(neopentylsulfinyl)aniline directing group that promotes rapid palladium‐catalyzed C–H acetoxylation and alkenylation of arylacetamides has been developed. The acetoxylation reaches completion within only 40 min at 100 °C and leads to the bis‐functionalized products. Alternatively, the reaction can be carried out at room temperature, which is beneficial for sensitive substrates. For the alkenylation, we have developed a protocol in which easily available 1‐substituted cyclopropanols were employed as equivalents of vinyl ketones. [ABSTRACT FROM AUTHOR] more...

A novel and efficient approach has been developed for the synthesis of a diverse range of hydroxyisoindolo[1,2‐b]benzothiadiazinedioxide derivatives through a sequential palladium catalyzed cross‐dehydrogenative coupling (CDC) and intramolecular cyclization. This method works not only with aryl aldehydes and alcohols but also with toluene to generate angularly fused heterocycles in good to excellent yields. [ABSTRACT FROM AUTHOR] more...

A convenient and efficient CoIII‐catalyzed cyclization of 2‐arylquinazolinones with alkynes is described. The electron donating as well as withdrawing groups and also halide substituted quinazolinones are compatible with this reaction. This catalytic reaction is highly regioselective with unsymmetrical alkynes. A possible mechanism, involves a formation of five‐membered metallacycle I by metal‐catalyzed aromatic C–H bond activation, alkyne insertion, seven‐membered metallacycle intermediates followed by reductive elimination to give a final product. [ABSTRACT FROM AUTHOR] more...

An effective Pd(II)/Ag(I)‐promoted intramolecular cross‐dehydrogenative coupling (CDC) of substituted 1‐benzylimidazoles under air provides, for the first time, a simple access to several functionalized imidazo[2,1‐a]isoindoles, an interesting class of polycyclic heteroaromatic compounds. The direct involvement of two unactivated carbon–hydrogen bonds, without any directing group, grants an elevated atom economy of the whole process. [ABSTRACT FROM AUTHOR] more...

A reaction mode on carbene bridging C–H activation (CBA) is described. In this reaction, metal carbene was produced prior to the event of C–H bond metallation. Readily available aryl dizaoesters were employed as the carbene precursors. Migratory insertion of the palladium carbene intermediate could create a modular bridging arm to promote the C–H bond palladation of tethered aldehyde moiety. Its synthetic potential was demonstrated by facile construction isocoumarin scaffold from easily accessible starting materials. Furthermore, this protocol is also amenable for late‐functionalization of complex molecules. [ABSTRACT FROM AUTHOR] more...

A method to achieve rhodium(III)‐catalyzed, potassium acetate enabled intermolecular C–H amination of ketoximes using various benzenesulfonamide, especially 4‐nitrobenzenesulfonamide is reported. Various aryl ketoximes substituted with electron‐withdrawing functional groups were all well tolerated and produced the corresponding products in moderate to good yields. A preliminary mechanistic study revealed that potassium acetate is essential to realizing intermolecular amination. [ABSTRACT FROM AUTHOR] more...

Discovered the Ruthenium(II) catalysed highly stereo‐ and regioselective protocol for the oxidative C‐3 alkenylation of indolizines and pyrrolo[1,2‐a]quinolines. The methodology represents the first example for the directing group assisted C–C bond formation reaction of the indolizines. Under mild reaction conditions, this method provides an ample substrate scope to produce C‐3 alkenyl indolizines in excellent to moderate yields. However, pyrrolo[1,2‐a]quinolines underwent alkenynation at elevated temperature to furnish C‐3 alkenyl derivatives. The functionalized indolizines were selectively reduced to obtain their saturated derivatives. [ABSTRACT FROM AUTHOR] more...

The regio‐ and chemo‐selective Pd‐catalyzed C–H activation methods have been successfully reported for directed C–H sulfonation and halogenation of pyridazinedione with arylsulfonyl chlorides and N‐halosuccinimide, respectively. These protocols are compatible with a range of various functional groups and exhibit excellent regio‐selectivity under mild reaction conditions by use of inexpensive and readily accessible reagents. [ABSTRACT FROM AUTHOR] more...

The stereoselective syntheses of spirobicyclic and tetracyclic pyrazolidinones are reported based on a (3+2) annulation between hydrazones and α‐oxoketenes. Some of these conformationally constrained molecules were resolved as enantiopure materials by HPLC techniques and evaluated as aminocatalysts for iminium activation in a model Diels–Alder cycloaddition. [ABSTRACT FROM AUTHOR] more...

A catalyst‐ and additive‐free simple and straightforward method for regioselective direct sp2 C–H acetoxylation reaction of aldehyde hydrazones has been achieved at ambient temperature employing PIDA as an acetoxy source. The scope of the reaction has been successfully verified with a wide range of biologically important aldehyde hydrazones with diverse functional group tolerance. The method is highly selective, mild and efficient, operationally simple, rapid and high‐yielding. [ABSTRACT FROM AUTHOR] more...

A facile and efficient synthesis of 1H‐indazoles and 1H‐pyrazoles through a copper‐promoted oxidative intramolecular C–H amination of hydrazones using a cleavable directing group was developed. This reaction is characterized by its mild conditions, operational simplicity, readily available reagents, and excellent yields. A tentative mechanism for Cu‐mediated C–H oxidative amination was proposed. [ABSTRACT FROM AUTHOR] more...

A palladium‐catalyzed chelation‐assisted selective ortho C‐H bond olefination of biologically active 4H‐benzo[d][1,3] oxazin‐4‐one derivatives with activated olefins has been achieved. The products are obtained in good yields with high regio‐ and stereoselectivities. This new protocol has been demonstrated to provide a variety of olefinated‐4H‐benzo[d][1,3]oxazin‐4‐one derivatives. The site selectivity of the reaction was explained by a DFT study. [ABSTRACT FROM AUTHOR] more...

The formation of the C–O bond is one of the hot topics in the area of C(sp3)–H bond functionalization. A metal‐free oxidative cross‐coupling between benzylic C(sp3)–H bond and carboxylic acids has been developed. The reactions were performed with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as the catalyst, tert‐butyl nitrite (TBN) as the co‐catalyst, and molecular oxygen as the terminal oxidant. A variety of diarylmethanes could be successfully coupled with various carboxylic acids to obtain diarylmethanol esters in good to excellent yields. In addition, 2‐benzylbenzoic acids could be converted into phthalides in moderate yields through an intramolecular oxidative cyclization. [ABSTRACT FROM AUTHOR] more...

Herein, we report that palladium‐catalyzed C‐H bond activation can overcome some of the challenges in the preparation of π‐extended aromatics containing one or two heteroelements, which are important structures in organic materials science. The sequential palladium‐catalyzed intermolecular direct C5‐arylation of heteroarenes by aryl bromides, followed by bromination of the heteroarene unit with N‐bromosuccinimide, and finally palladium‐catalyzed intramolecular direct arylation allowed the synthesis of the desired phenanthro[9,10‐b]thiophenes, phenanthro[9,10‐b]furans, phenanthro[9,10‐b]thiazoles, acenaphtho[1,2‐d]thiophenes, and acenaphtho[1,2‐d]thiazoles in only three steps. [ABSTRACT FROM AUTHOR] more...

4‐Quinolone derivatives are serving as active components in diverse families of drugs such as antibacterial, antiviral, antimalarial, anticancer, antitumor and anti‐HIV agents. They have also attracted the significant attention in synthetic chemistry due to their prolific development, pharmacokinetic properties and good tolerability. Recent years have observed an upsurge in the modification of the 4‐quinolone scaffold. This review covers (2002 to 2019) the progress of the developments in the syntheses as well as functionalization of 4‐quinolones in different positions. [ABSTRACT FROM AUTHOR] more...

Development of sustainable and economically viable methods is challenging but desired in organic synthesis. Herein, intramolecular C(sp3)–H imination between a free amine group and N‐methylene group is established using TBAI (20 mol %)‐TBHP (3.0 equiv.) in DMSO which is found to be an inexpensive replacement of PhI‐mCPBA in HFIP. [ABSTRACT FROM AUTHOR] more...

Here in we report, rhodium(III)‐catalyzed decarboxylative acylation of arenes using α‐oxocarboxylic acids as acyl surrogate. In this strategy, O–NHAc group act as an autocleavable oxidizing directing group (ODGauto), thus giving rise to ortho‐acylated phenols in moderate to good yields. Mechanistic studies provided strong support for a kinetically relevant C–H bond activation. According to the best of our knowledge, this is the first report of Rhodium catalyzed decarboxylative acylation. [ABSTRACT FROM AUTHOR] more...

Palladium‐catalyzed remote meta‐selective C‐H functionalization of arylacetic acid has been developed using a pyrimidine template. This transformation is not only tolerated to a diverse range of arylacetic acid and alkene substrates but also applicable to the synthesis of pharmaceutically active ibuprofen derivatives. Moreover, the pyrimidine template was readily removable and recyclable under mild conditions. [ABSTRACT FROM AUTHOR] more...

The iridium‐catalyzed aromatic C–H alkylation followed by intramolecular annulation reactions between N‐aryl‐2‐aminopyridines and sulfoxonium ylides for the synthesis of 2‐alkyl indoles is described. This highly efficient and step‐economical cyclization reaction displays excellent functional group compatibility and regioselectivity. Afterwards, the directing group in C–H alkylation can be readily removed to obtain the free N–H indoles. Thus, the sulfoxonium ylide, a carbene precursor, is proved as a useful surrogate of diazo compounds in C–H activation chemistry. [ABSTRACT FROM AUTHOR] more...

A CuII‐mediated ortho‐C–H nitration using amide‐oxazoline as the directing group has been developed. The reactions utilize sodium nitrite as the source of the nitro group under O2 atmosphere and proceed smoothly. The desired products can be obtained in yields of 26–94 %. [ABSTRACT FROM AUTHOR] more...