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The transformation of a single C−F bond of trifluoromethylarenes bearing a hydrosilyl group at the ortho position was achieved. The activation of the hydrosilyl group with a trityl cation in the presence of nucleophiles allowed for selective C−F bond functionalization, for example, by allylation, carboxylation, or chlorination. Further derivatization of the resulting fluorosilylarenes afforded various aromatic difluoromethylene compounds.

The reactivity of the azomethine ylides in cycloaddition reactions is improved by the presence of electron-deficient aromatic rings as well as the presence of ortho substituents relative to the aminomethyl group.

An oxidative coupling reaction of isocyanides and methylbenzenes using tetrabutylammonium iodide as a catalyst affords the corresponding benzamides.

The binary zirconium and hafnium polyazides [PPh4]2[M(N3)6] (M=Zr, Hf) were obtained in near quantitative yields from the corresponding metal fluorides MF4 by fluoride–azide exchange reactions with Me3SiN3 in the presence of two equivalents of [PPh4][N3]. The novel polyazido compounds were characterized by their vibrational spectra and their X-ray crystal structures. Both anion structures provide experimental evidence for near-linear M-N-N coordination of metal azides. The species [M(N3)4], [M(N3)5]− and [M(N3)6]2− (M=Ti, Zr, Hf) were studied by quantum chemical calculations at the electronic structure density functional theory and MP2 levels.

The imidazolin-2-imino group is an N-heterocyclic imino functionality that derives from the class of compounds known as guanidines. The exocyclic nitrogen atom preferably bonds to electrophiles and its electron-donating character is markedly enhanced by efficient delocalization of cationic charge density into the five-membered imidazoline ring. Thus, this imino group is an excellent choice for thermodynamic stabilization of electron-deficient species. Due to the variety of available imidazoline-based precursors to this ligand, its steric demand can be tailored to meet the requirements for kinetic stabilization of otherwise highly reactive species. Consequently, it does not come as a surprise that the imidazolin-2-iminato ligand has found widespread applications in transition-metal chemistry to furnish pincer complexes or “pogo stick” type compounds. In comparison, the field of main-group metal compounds of this ligand is still in its infancy; however, it has received growing attention in recent years. A considerable number of electron-poor main-group element species have been described today which are stabilized by N-heterocyclic iminato ligands. These include low-valent metal cations and species that are marked by formerly unknown bonding modes. In this article we provide an overview on the present chemistry of main-group element compounds of the imidazolin-2-iminato ligand, as well as selected examples for the related imidazolidin- and benzimidazolin-2-imino system.

An efficient copper-mediated etherification of inert C–H bonds of (hetero)arenes with reagent-amounts of alkoxysilanes and alkanols has been developed using (2-aminophenyl)pyrazole (2-APP) as a removable directing group. The reaction is scalable, rapidly proceeds under an open atmosphere, and tolerates diverse functional groups to provide alkyl aryl ethers in high yields (up to 87%). As an application, the formal synthesis of anti-emetic drug metoclopramide is accomplished.

A diverse range of benzotriazoles were synthesized from various 3-(azidoalkoxy)aryne precursors, which were easily prepared by Mitsunobu etherification. Various bis-1,2,3-triazoles containing a benzotriazole skeleton were obtained via sequential azide–alkyne and azide–aryne cycloadditions. Intramolecular azido–aryne cycloaddition, conducted using the same starting materials, afforded new types of ring-fused benzotriazoles. In the latter case, the reaction proceeded efficiently even though the regioorientation of the azido group was the reverse of that usually observed in intermolecular reactions between 3-alkoxyarynes and an azide.

A visible-light-induced C-3 selective trifluoroethylation of imidazoheterocycles using 1,1,1-trifluoro-2-iodoethane as trifluoroethyl radical sources was developed. The methodology enables the introduction of a trifluoroethyl group in a fast and efficient reaction under mild conditions with excellent regioselectivities and high functional group tolerance.

A two-step synthetic strategy toward difluoromethyl ethers via a CuI-catalyzed reaction of the alcohols, bearing additional protected functionalities, with FSO2CF2CO2H has been developed. The high potential of the developed protocol has been shown by preparing novel OCF2H-analogues of GABA and l-proline. The described transformation has good functional group compatibility and can serve as a powerful synthetic tool for late-stage preparation of complex OCF2H-containing organic compounds as well as building blocks for drug discovery.

A highly controlled ring opening of siloxydifluorocyclopropanes, formed by nBuN4Br-catalyzed difluorocyclopropanation of methyl vinyl ketones bearing a β-alkylthio group by using TMSCF2Br as a unique difluorocarbene source, results in metal difluorohomoenolates with assistance of copper or silver followed by an intramolecular addition and elimination reaction leading to α-gem-difluorocyclopentenones efficiently.

A remote OH group-directed metal-free transformation of alkynes to carbonyl compounds has been developed. Using only HOAc and EtOH solvent, this reaction elegantly converts alkynes into valuable ketones by remote hydroxyl group activation. Through comparison and isotope labeling experiments, it was confirmed that the process operates via a hydration reaction involving an acetic acid molecule, instead of a water molecule.

This review highlights a number of recent developments in the field of main group enantioselective catalysis. Many essential transformations can be effected catalytically such as hydrosilylation, hydroamination and hydrogenation reactions, amongst others, in an asymmetric fashion using earth abundant s- and p-block elements such as calcium, strontium, boron and aluminum. Recent work in this area has shown that these systems are not only active in catalysis but may also have the potential to compete with transition metal based systems with the reduced cost and toxicity sometimes associated with main group chemistry.

The synthesis of alpha-benzamido-alpha-benzyl lactones 23 of various ring size was achieved either via ‘direct amide cyclization’ by treatment of 2-benzamido-2-benzyl-omega-hydroxy-N,N-dimethylalkanamides 21 in toluene at 90 – 110° with HCl gas or by ‘ring transformation’ of 4-benzyl-4-(omega-hydroxyalkyl)-2-phenyl-1,3-oxazol-5(4H)-ones under the same conditions. The precursors were obtained by C-alkylations of 4-benzyl-2-phenyl-1,3-oxazol-5(4H)-one (15) with THP- or TBDMS-protected omega-hydroxyalkyl iodides. Ring opening of the THP-protected oxazolones by treatment with Me2NH followed by deprotection of the OH group gave the diamides 21, whereas deprotection of the TBDMS series of oxazolones 25 with TBAF followed by treatment with HCl gas led to the corresponding lactones 23 in a one-pot reaction.

The reaction of primary, secondary, phenyl, allyl, and benzyl trityl ethers with lithium chloride in methanol at reflux led to deprotection of the trityl group affording the corresponding alcohol in good to excellent yields under mild reaction conditions.

A number of N-heterocycles have been tested as directing group in the novel Ru-catalyzed regioselective ortho-selenylation of benzene featuring 2-pyridinyl and 1-pyrazolyl groups as most promising candidates that have been further examined in a broad variety of arenes.

β-Diketiminate (BDI) ligands are widely used supporting ligands in modern organometallic chemistry and are capable of stabilizing various metal complexes in multiple oxidation states and coordination environments. This review describes recent advances in the chemistry of group 5 metals, namely vanadium, niobium and tantalum supported by the BDI ligand framework. Special emphasis is put on the reactivity of low-valent complexes, as well as low-coordinate complexes containing reactive multiply bonded groups, such as alkylidene, imido and nitrido groups.

The synthesis of (.+-.)-aureothin (I) as well as imino (Ib,c) or keto group (Id) derivatives thereof is presented.

Because of the unique properties of the trifluoromethoxy group, molecules bearing this moiety will find applications in various fields, particularly in the life sciences. However, despite the great interest in this functional group, only a small number of trifluoromethoxylated molecules are currently synthetically accessible. Over the last few years, several innovative and promising strategies for the synthesis of trifluoromethoxylated compounds have been described. This Minireview discusses these existing methods with a particular focus on more recent advances.

Pd(OAc)2-catalyzed acetoxylations of 3-aryl or 3-alkyl groups mounted on a 2-isoxazoline ring were studied. Ortho-selective C–H bond activation directed by an isoxazolinyl group was realized. 2-Isoxazoline rings without and with one or two alkyl substituents in the 5-position were effective directing groups. The substituent effect on reactivity and regioselectivity was examined. The acetoxylation was applied to the synthesis of useful intermediates.

The 3-butenyloxycarbonyl group can be introduced into carbohydrates such as (I) under mild conditions.

New Tl type-I clathrates of K7.62(1)Tl0.38(1)Ge45.34(3) and Rb7.50(1)Tl0.50(1)Ge46 were synthesized via solid-state reaction. Rb7.50(1)Tl0.50(1)Ge46 and K7.62(1)Tl0.38(1)Ge45.34(3) were found to crystallize in space groups Pmn and Iad with lattice parameters of a = 10.81559(7) A and a = 21.4290(2) A, respectively. Theoretical calculations indicated metallic features based on the calculation models of Rb7Tl1Ge46 and K7Tl1Ge46 in the space group of Pm. The densities of states at the Fermi level were predominantly determined by the Ge s and Ge p orbitals of Rb7Tl1Ge46 and K7Tl1Ge46.

The cyano group is well known as a versatile intermediate for transformations into a multitude of useful functional groups such as carboxyl, carbamoyl, aminomethyl, carbonyl, and heterocycles. Moreover, benzonitriles and α-aminonitriles are practical synthetic and natural scaffolds. This paper reviews catalytic methodologies for direct cyanation reactions of C–H bonds. These are classified by the cyano-group sources and are sorted into three categories: (i) organic cyano-group sources, (ii) metallic cyano-group sources, and (iii) combined cyano-group sources. This review includes all the reported methods in the literature until the beginning of 2016.

The pharmacological importance of 2-quinolinone derivatives is well known. Herein, we developed an effective protocol for the synthesis of 2-quinolinone derivatives by palladium-catalyzed sequential β-C(sp3)–H arylation and selective intramolecular C(sp2)–H/N–H amination starting with aryl iodides and carboxylic acids. A novel directing group, glycine dimethylamide, was used in the synthesis. We synthesized various quinolinone derivatives, including 5-substituted quinolinones, which are difficult to obtain using the traditional pathway. The directing group could be easily removed and could be readily transformed into other useful functional groups.

Systematic explorations of new phases in the Ag+–Ti4+/Zr4+/Nb5+/Ta5+–Se4+–O(F) system by hydrothermal syntheses or standard high temperature solid-state reactions resulted in four new mixed-metal silver selenites, namely, Ag3Ti3O3(SeO3)4F (1, P63), Ag2ZrF2(SeO3)2 (2, Cmca) and AgMO(SeO3)2 (M = Nb, 3; Ta, 4) in the space group Cmcm. Ag3Ti3O3(SeO3)4F features an interesting [Ti3O3(SeO3)4]2− 3D anionic framework composed of 1D chains of corner-sharing TiO6 octahedra which are further interconnected by tridentate bridging SeO32− anions, displaying 1D hexagonal channels of Ti6Se6 12-member rings (MRs) along the c-axis, filled by the Ag+ cations and isolated F− anions. More interestingly, it displays a moderate strong Second-Harmonic Generation (SHG) response about 2 times that of KH2PO4 (KDP). Compound 2 features a novel 1D [ZrF2(SeO3)2]2− anionic chain composed of edge-sharing ZrO4F4 polyhedra in which two neighboring Zr4+ cations are further bridged by a pair of selenite anions. Compounds 3 and 4 are isostructural and their structures feature 1D anionic chains of [MO(SeO3)2]− (M = Nb, Ta) which are separated by Ag+ cations, the 1D [MO(SeO3)2]− (M = Nb, Ta) chain is formed by 1D chains of corner-sharing MO6 (M = Nb, Ta) octahedra in which two neighboring metal centers are also bridged by a pair of selenite anions. Other characterizations including thermal analyses, optical and luminescence property measurements have also been performed.

Yields of mono- as well as bis-acetoxylated arenes depend significantly on the electronic nature of aryl substituents.

The reactions between group 12 metals and the acidic TaF 5 were studied in the anhydrous HF (aHF) solvent. We were able to prepare and characterize the first compounds containing metal M 2+ cations and undecafluoridodimetallate anions – M(Ta 2 F 11 ) 2 (M = Cd, Hg) without the additional cations, anions or ligands included in the crystal structure. They both crystallize in P -1 space group with cell parameters a = 9.1571(4) A, b = 9.8750(3) A, c = 10.9400(7) A, α = 94.389(4)°, β = 113.124(5)°, γ = 101.142(3)°, V = 879.81(8) A 3 , Z = 2, T = 150 K (Cd(Ta 2 F 11 ) 2 ) and a = 9.1381(5) A, b = 9.8613(6) A, c = 11.4470(7) A, α = 114.086(6)°, β = 102.290(5)°, γ = 100.398(5)°, V = 877.84(11) A 3 , Z = 2, T = 150 K (Hg(Ta 2 F 11 ) 2 ). Metal cations connected through two anions form chains along b axis. M(HF) 2 (TaF 6 ) 2 . nHF (M = Cd, Hg) compounds were also prepared in the MF 2 /TaF 5 (M = Cd, Hg) system and their crystal structures were determined.

A ligand-assisted gold-catalyzed regiodivergent intramolecular hydroarylation of alkynes by means of a directing group is described which tolerates various aryl, hetaryl and alkyl and even steroidal substituents.

This review focuses on the most recent advances in the field of transition-metal-catalyzed direct intermolecular C−H amidation and amination of arenes. The manuscript is divided into two parts according to whether or not external oxidants are required. The first part includes the cases of simple neutral amines, amides, or sulfonamides in combination with external oxidants. The second section contains the examples of preactivated amino sources in the absence of any external oxidants. In each part, the content is classified in line with the different types of transition-metal catalysts used, including Rh, Ru, Ir, Pd, Cu, Ni, Co, and Fe. In addition, the substrate scope and limitations as well as catalytic mechanism are discussed.

Herein, we report a convenient synthesis of aryl-substituted (E)-vinylic NH-sulfoximines via the Horner–Wadsworth–Emmons reaction without the use of protection–deprotection group strategies.

The reaction of perfluorinated 3,5-dioxoesters with 1,2-diaminobenzenes or 2,3-diaminonaphthalenes afforded two types of 1H-benzo-1,5-diazepine derivatives containing a perfluorinated side chain. 2,5-Dihydro-1H-benzo-1,5-diazepin-2-ones were formed by cyclocondensation via the central keto and the ester group, whereas 1H-benzo-1,5-diazepines resulted from cyclocondensation via the two keto groups. The tautomerism and isomerization of these compounds have been investigated by 1H-, 13C-, and 19F-NMR spectroscopy. The 1,5-diazepines appear in CDCl3 solution as mixtures of two tautomeric forms, the enaminoimine I and diaminodiene II. In DMSO solution, besides I and II, two further species, III and IV, are formed by (E/Z) isomerization on the exocyclic C=C bond.

A straightforward and efficient method has been developed for the synthesis of 2-benzylbenzaldehyde derivatives from 2-methylbenzaldehyde and iodobenzene via a C(sp3)–H activation process. In the course of the activation reaction, acetohydrazone is formed between 2-benzylbenzaldehyde and acetohydrazine as a transient directing group. As a new kind of transient directing group, acetohydrazone exhibits a remarkable directing effect to give corresponding products in good to excellent yields.

A new method was developed to synthesize N2-alkyl-substituted 1,2,3-triazole through N-iodosuccinimide (NIS) mediated iodofuctionalization reaction of the alkene group with bi-, mono-, and unsubstituted NH-1,2,3-triazoles. The favored N-1 type hydrogen bond between the iodonium ion intermediate and 1,2,3-triazole was supposed to be generated, which gave the desired N2-alkyl triazole with a high N2-selectivity.

A concise, catalytic, and general strategy that allowed efficient total syntheses of 22 natural 13-methylprotoberberines within four steps for each molecule is reported. This synthesis represents the most efficient and shortest route to date, featuring three catalytic processes: CuI-catalyzed redox-A(3) reaction, Pd-catalyzed reductive carbocyclization, and PtO2 -catalyzed hydrogenation. Importantly, this new strategy to the tetracyclic framework has also been applied to the collective concise syntheses of >30 natural protoberberines (without 13-methyl group) and five aporhoeadane alkaloids.

Carbazole preferentially reacts with the fluorine group of fluorinated iodoarenes to form iodinated N-arylcarbazole intermediates.

2-Aminophenyl-1H-pyrazole was discovered as a removable bidentate directing group for copper-mediated aerobic oxidative C(sp2–H) bond amidation and sulfonamidation. When Cu(OAc)2 was employed as the copper source and 1,1,3,3-tetramethylguanidine as an organic base, the reaction, optimally carried out overnight in DMSO at 80 °C in open air, produced a variety of amides and sulfonamides in moderate to excellent yields. This directing group has proven to be particularly efficient in C–H sulfonamidation.

The transition-metal-catalyzed direct triflation of naphthyl amides and naphthyl ketones has been accomplished for the first time. Benzophenone (BP) was found to be a suitable ligand for the cross-coupling reactions. Density functional theory (DFT) calculations revealed that excessive amounts of HOTf inhibit the reductive elimination of the C–F bond to realize the unusual reductive elimination of the C–OTf bond.

The OCF3 group is of high interest in the quest for new drugs and agrochemicals, thanks to its atypical features. This Highlight article depicts the recent and impressive advances toward the synthesis of OCF3-containing molecules.

In contrast to the conventional group transfer polymerization (GTP) using a catalyst of either an anionic nucleophile or a transition-metal compound, the organocatalyzed GTP has to a great extent improved the living characteristics of the polymerization from the viewpoints of synthesizing structurally well-defined acrylic polymers and constructing defect-free polymer architectures. In this article, we describe the organocatalyzed GTP from a relatively personal perspective to provide our colleagues with a perspicuous and systematic overview on its recent progress as well as a reply to the curiosity of how excellently the organocatalysts have performed in this field. The stated perspectives of this review mainly cover five aspects, in terms of the assessment of the livingness of the polymerization, limit and scope of applicable monomers, mechanistic studies, control of the polymer structure, and a new GTP methodology involving the use of tris(pentafluorophenyl)borane and hydrosilane.

Achieving selective C−H activation at a single and strategic site in the presence of multiple C−H bonds can provide a powerful and generally useful retrosynthetic disconnection. In this context, a directing group serves as a compass to guide the transition metal to C−H bonds by using distance and geometry as powerful recognition parameters to distinguish between proximal and distal C−H bonds. However, the installation and removal of directing groups is a practical drawback. To improve the utility of this approach, one can seek solutions in three directions: 1) Simplifying the directing group, 2) using common functional groups or protecting groups as directing groups, and 3) attaching the directing group to substrates via a transient covalent bond to render the directing group catalytic. This Review describes the rational development of an extremely simple and yet broadly applicable directing group for PdII, RhIII, and RuII catalysts, namely the N-methoxy amide (CONHOMe) moiety. Through collective efforts in the community, a wide range of C−H activation transformations using this type of simple directing group have been developed.

Palladium-catalyzed C-H alkylation reaction with alkylboronic acids has successfully been developed using a removable pyridyldiisopropylsilyl directing group. The amino acid played a crucial role as a ligand in the reaction. The alkylation protocol is also applicable to the coupling of C(sp(3))-H bonds with alkylboronic acids.

The chemistry of the SF5CF2 moiety has been scarcely investigated. In this report, we present synthetic pathways to a variety of SF5CF2-substituted compounds starting from vinyl ethers and SF5CF2C(O)Cl. In specific chemical environments and under particular reaction conditions, the SF5CF2 moiety is unstable in downstream products resulting in the elimination of the SF5– anion and its decomposition to SF4 and F–. Surprisingly, the formed F– can attack the intermediate difluorovinyl moiety to form trifluoromethyl substituted products. This appears to happen when an intermediate neighboring group participation involving a double bond is possible. Under slightly different conditions, the reaction stops at the stage of a difluorovinyl compound.

Organic selenides were efficient regioselective synthesized by palladium-catalyzed switchable mono- and diselenylation of arenes sp 2 C–H bonds through simply tuning the DMSO to water ratio. The present protocol was also successfully extended to the monoselenylation of 2-phenoxypyridines, which bore a removable directing group, in modest yields.

A Rh(III)-catalyzed C–H ortho-mono-olefination of aryls directed by 7-azaindoles was reported. This method opens up a novel pathway to synthesize complex 7-azaindole derivatives and interestingly, we observed an intramolecular cascade annulation via unexpected double directing groups (7-azaindole and carbonyl).