Abstract: α,β-Unsaturated O-pivaloyl oximes are coupled to alkenes by Rh(III) catalysis to afford substituted pyridines. The reaction with activated alkenes is exceptionally regioselective and high-yielding. Mechanistic studies suggest that heterocycle formation proceeds via reversible C–H activation, alkene insertion, and a C–N bond formation/N–O bond cleavage process.

Abstract: Bis(imino)pyridine cobalt methyl complexes are active for the catalytic hydroboration of terminal, geminal, disubstituted internal, tri- and tetrasubstituted alkenes using pinacolborane (HBPin). The most active cobalt catalyst was obtained by introducing a pyrrolidinyl substituent into the 4-position of the bis(imino)pyridine chelate, enabling the facile hydroboration of sterically hindered substrates such as 1-methylcyclohexene, α-pinene, and 2,3-dimethyl-2-butene. Notably, these hydroboration reactions proceed with high activity and anti-Markovnikov selectivity in neat substrates at 23 °C. With internal olefins, the cobalt catalyst places the boron substituent exclusively at the terminal positions of an alkyl chain, providing a convenient method for hydrofunctionalization of remote C-H bonds.

Abstract: Metal-free: The first metal-free aryltrifluoromethylation of activated alkenes has been developed. With this method, trifluoromethylated isoquinolinediones, spirobicycles, oxindoles, and α-aryl-β-trifluoromethylamides were obtained with high control of the regioselectivity.

Abstract: Herein we report a metal-free method for the direct anti-Markovnikov hydroamination of unsaturated amines. Irradiation of the amine substrates with visible light in the presence of catalytic quantities of easily synthesized 9-mesityl-10-methylacridinium tetrafluoroborate and thiophenol as a hydrogen-atom donor furnished the nitrogen-containing heterocycles with complete regiocontrol. Two examples of intermolecular anti-Markovnikov alkene hydroamination are also disclosed.

Abstract: 'N' front and center: The facile construction of C-N bonds by the generation of nitrogen-centred radicals from N-fluorobenzenesulfonimide results in the aminative difuctionalization of alkenes. The first copper-catalyzed intermolecular aminocyanation of alkenes and diamination of styrenes were realized. Si-F and B-F interactions play a significant role in the reaction.

Abstract: The trifluoromethyl group is of great interest in pharmaceutical chemistry, agrochemistry, and materials science because of its unique properties, and great efforts have been made to develop reactions for its introduction into organic molecules. Indeed, many methods for formation of not only Csp2 CF3, but also Csp3 CF3 bonds have been developed. Nevertheless, new synthetic methods to form C CF3 bonds, especially Csp3 CF3 bonds, in a wider range of molecular contexts are still needed. Regarding trifluoromethylation of the C=C bond, a notable development has been the deprotonative trifluoromethylation of simple alkenes, a method reported in 2011 (Scheme 1a). In contrast, we recently reported the trifluoromethylation of allylsilanes using the CuI/Togni s reagent (1) system. Based on the resulting mechanistic insight, oxytrifluoromethylation of styrene derivatives was achieved under mild reaction conditions and direct synthesis of b-trifluoromethylstyrene derivatives from styrenes was demonstrated. Szab and co-workers also independently studied the oxytrifluoromethylation of multiple bonds with the CuI/1 system, and Zhu and Buchwald developed an intramolecular reaction of simple alkenes in the wake of their deprotonative trifluoromethylation. Following from our previous studies, we investigated difunctionalization-type trifluoromethylation of the C=C bond, thus focusing on the use of carbon nucleophiles. In 2012, Liu and co-workers reported the palladium/ytterbiumcatalyzed oxidative aryl trifluoromethylation of activated alkenes using a combination of TMSCF3/CsF/PhI(OAc)2. [11] Although Liu s method provided structures bearing a trifluoromethyl group, only oxindole synthesis from a,b-unsaturated amide derivatives was demonstrated. Other types of carbocycles and heterocycles, such as indane, tetralin, indoline, and tetrahydroquinoline, are also found in many bioactive compounds, and their trifluoromethylated derivatives may exhibit altered potency. It is well known that treatment of an alkene bearing allylic protons under trifluoromethylation conditions provides the deprotonative trifluoromethylation product (Scheme 1a). Difunctionalization-type trifluoromethylation of unactivated alkenes, especially those having allylic protons, is still challenging (Scheme 1b). Based on our previous mechanistic insights, 8] we considered that the acceleration of the reaction by orbital interactions between the alkene and aryl group would favor the desired trifluoromethylation reaction coupled with intramolecular C C bond formation. Herein we report the copper-catalyzed carbotrifluoromethylation of simple C=C bonds, using the Cu/1 system, as well as a unique 1,6-oxytrifluoromethylation reaction. To achieve carbotrifluoromethylation of a simple alkene bearing allylic protons, it is important to prevent competitive deprotonative trifluoromethylation of the alkene. Compound 2a was used as a test substrate for the screening of reaction conditions (Table 1). Use of [(MeCN)4Cu]PF6 in CH2Cl2 at room temperature selectively afforded the deprotonative trifluoromethylation product 4a in low yield (entry 1). The carbotrifluoromethylation product 3a was obtained in 18% yield in 1,2-dichloroethane (DCE) at 80 8C, but 4a was again the major product (entry 2). SurprisScheme 1. a) Reported electrophilic trifluoromethylation. b) Trifluoromethylation coupled with construction of carbocycles and heterocycles.

Abstract: Nanostructured carbon-based materials have shown high catalytic activity in several important reactions and related chemical industrial processes, such as direct or oxidative dehydrogenation of hydrocarbons and Friedel–Crafts reactions. Nanocarbon materials exhibit significant advantages over traditional metal or metal oxide based catalysts because of their tunable acidity/basicity, electron density, and convenient recycling and reusability, and they have been shown to be potential alternatives to conventional catalysts to meet the requirements of sustainable chemistry. As a result, the field of nanocarbon catalysis has been experiencing an unparalleled development of new catalyst synthesis or their applications in new reaction systems. However, there is only slow growth of mechanistic interpretation of carbon-catalyzed reactions, which is even more urgent to advance our knowledge in related fields. Present research on the mechanism of carbon catalysis suggests that oxygen containing functional groups, especially ketonic carbonyl groups on nanocarbon, which are rich in electrons, may act as the catalytic active sites for oxidative dehydrogenation (ODH) of alkanes to corresponding alkenes. The reaction process is assumed to be similar to that for transition-metal oxide catalysts. The C H bonds of alkanes dissociate at active oxygen functional groups, and the hydrogen atoms are abstracted by Lewis base sites. After the desorption of alkene products, gas-phase O2 reacts with the abstracted hydrogen to form H2O, then the active catalytic sites are regenerated to finish one catalytic cycle. The above unspecific catalytic mechanism is only based on the qualitative characterization of carbon catalysts, while the identity of the active sites or a detailed kinetic study has never been executed with direct and convincing chemical evidence. One of the most critical problems that limits the quantitative description of the catalytic mechanism is the uncertainty of the chemical structure of nanocarbon materials. The coexistence of several kinds of surface functional groups (such as hydroxyl, carbonyl, and carboxylic acid groups) is unavoidable, as the synthesis or the following surface modification procedures of nanocarbon catalysts are normally realized by a severe physical or chemical process, such as laser irradiation and oxidation by HNO3, O2, and O3. [8] There are still lack of reliable quantification methods for the surface functional groups on nanostructured carbon materials because of their complexity in type and quantity. As a result, turnover frequency (TOF), the ultimate parameter to evaluate the intrinsic activity of heterogeneous catalysts, is also rarely reported in the case of nanocarbon catalysts, making it impossible to study the detailed reaction kinetics or compare the activity of carbon catalysts bearing different structures fairly and objectively. The quantitative surface composition analysis is also desirable for the application of nanostructured carbon as a catalyst support or electrochemical devices, which takes an even larger proportion in the field of carbon materials, as the surface structure of nanocarbon materials is essential for their physical or chemical properties (for example, affinity for a certain metal or metal ion). In view of the quantification methods of oxygen functional groups, herein we propose a chemical titration method to determine the surface concentration of three kinds of typical oxygen functional groups ( C=O, C OH, and COOH) on the surface of carbon nanotubes (CNTs) (Scheme 1). Through selective deactivation of these specific oxygen functional groups and the assessment of the catalytic activity of different CNT derivatives for ethylbenzene (EB) ODH reactions, we provided chemical evidence to show that

Abstract: A novel approach for the synthesis of α,β- unsaturated ketones is developed tolerating a variety of functional groups on both aldehyde and alkene.

Abstract: The palladium-catalyzed synthesis of benzofurans and coumarins by reacting phenols and unactivated olefins is described.

Abstract: Against the rules: during the hundred years following Sabatier's groundbreaking work on catalytic hydrogenation, syn delivery of the H atoms to the π system of a substrate remained the governing stereochemical rule. An exception has now be found with the use of cationic [Cp*Ru] templates, which accounts for the first practical, functional-group-tolerant, broadly applicable and highly E-selective semihydrogenation method for alkynes.

Abstract: Background Transition metal–catalyzed alkene metathesis has revolutionized organic synthesis during the last two decades, even though the commonly used catalysts do not provide kinetic control over the stereochemistry of the newly formed double bonds. It is of utmost importance to fix this shortcoming, because the olefin geometry not only determines the physical and chemical properties of the alkene products but is also innately linked to any biological activities that the olefins may have. Advances Recent progress in catalyst design led to the development of a first set of metal alkylidene complexes of ruthenium, molybdenum, and tungsten that allow a host of inter- and intramolecular alkene metathesis reactions to be performed with good to excellent levels of Z selectivity (see the figure). This marks a considerable advancement over prior art, even though inherently E-selective catalysts remain elusive. In the case of disubstituted olefins, this gap in coverage can be filled by a sequence of alkyne metathesis followed by stereoselective semi-reduction of the resulting acetylene derivatives, which provides highly selective access to either geometrical series. Because the required alkylidyne catalysts have also been greatly improved in terms of activity, functional group tolerance, and user-friendliness, this method constitutes a valuable preparative complement. Advances in catalyst design solve a long-standing stereochemical issue. Alkene metathesis was tremendously successful in the past despite lacking catalyst control over the geometry (E versus Z) of the newly formed double bond. Recently introduced molybdenum (left), tungsten, and ruthenium (center) alkylidenes partly fix this problem as they allow preparation of Z-alkenes with high selectivity. Alternatively, either geometrical series can be accessed by alkyne metathesis followed by semi-reduction, which also benefits from new catalysts (right) of much improved performance. R, generic substituent; TBDPS, tert-butyldiphenylsilyl; Mes, mesityl; Ph, phenyl. Outlook It is expected that the new catalysts will be rapidly embraced by the synthetic community. Because the as-yet limited number of published case studies is very encouraging, it is reasonable to believe that more sophisticated applications to polyfunctionalized and/or industrially relevant targets will follow shortly. Such investigations will allow the selectivity and performance of the stereoselective metathesis catalysts to be scrutinized in great detail. In parallel, growing mechanistic insights into their mode of action will almost certainly be forthcoming that can then be translated into refined ligand design. The resulting feedback loops will likely result in the evolution of ever more selective and practical catalysts, the long-term impact of which on organic synthesis and materials science will surely be profound and lasting.

Abstract: Molecular-defined catalysts allow for the refinement of readily available feedstocks to more complex functionalized products. Prime examples for such transformations are carbonylation processes, which make use of carbon monoxide—currently the most important C1 building block. In fact, carbonylations represent industrial core reactions for converting various bulk chemicals into a diverse set of useful products for our daily life. More specifically, the transitionmetal-catalyzed addition of carbon monoxide to olefins or alkynes in the presence of a suitable nucleophile, such as water, alcohols, and amines, leads to the formation of saturated or unsaturated carboxylic acid derivatives. Nowadays, palladium is one of the most commonly employed metals in these transformations. Compared with the reaction of olefins, carbon monoxide, and alcohols (hydroesterification) or water (hydrocarboxylation), related aminocarbonylations leading to amides have received much less attention. The same is also true compared to the well-studied aminocarbonylation of alkynes, intramolecular aminocarbonylation of alkenes, and aminocarbonylation of aryl and vinyl halides. This is somewhat surprising as the aminocarbonylation of olefins provides a 100% atom-efficient route for producing carboxamides, which represent versatile building blocks and intermediates for the chemical, pharmaceutical, and agrochemical industries. In early studies of aminocarbonylations, cobalt-carbonyl complexes or nickel cyanide were used as catalysts. Ironcarbonyl complexes and ruthenium chloride also showed some catalytic activity. However, all these reactions were carried out under very severe conditions (> 200 8C; > 150 atm). Since the 1980s, more effective catalysts, such as ruthenium-carbonyl complexes and cobalt on charcoal, have been developed. Nevertheless, the substrate scope was limited and the reaction conditions were still harsh (150 8C; 70 atm). Notably, the formation of the corresponding formamide by-products was hardly suppressed. Hence, so far there exists no general and selective intermolecular aminocarbonylation of different olefins under mild conditions. Herein, we present an efficient homogeneous palladiumbased catalyst system for the aminocarbonylation of olefins with a variety of (hetero)aromatic amines or nitro compounds under relatively mild conditions. Notably, the corresponding products were obtained in high yield with good regioselectivity, and unwanted formamides were not observed. In our initial investigations we examined the effect of a series of phosphine ligands on the model reaction of 1octene (1a) with aniline (2a) and carbon monoxide. When monodentate ligands were used, no conversion or just trace amounts of the desired products were observed (Table 1, entries 1–4). Commercially available bidentate ligands (e.g. BINAP, Dppp, L2, and L4) showed low activity in the formation of the desired product (Table 1, entries 5–14). Hence, some of our own developed N-phenylpyrrole-based bisphosphine ligands with different steric properties were tested (Table 1, entries 15–17). To our delight, L10 was identified as the most promising ligand and the reaction afforded the desired product 3aa with moderate conversion, albeit with good selectivity. To improve the reaction further, we evaluated the influence of reaction parameters such as the molar ratio of 1a to 2a, acid co-catalyst, and solvent in the presence of L10 as the ligand. As shown in Table 1, the yield of 3aa was strongly affected by the molar ratio of 1a to 2a as a consequence of some isomerization of the olefin. Consequently, as the molar ratio of 1 a to 2a increased to 2:1, the yield of 3aa increased to 86% (Table 1, entry 18). Moreover, no reaction occurred in the absence of para-toluenesulfonic acid monohydrate (p-TsOH), thus indicating the importance of the acid for the generation of the catalytically active palladium hydride species (Table 1, entry 19). Interestingly, changing the THF solvent to toluene resulted in full conversion of 2a and gave nearly quantitative yields of the corresponding amides, as determined by GC (Table 1, entry 20). No conversion was observed and the starting materials were recovered in the absence of [Pd(acac)2] (acac = acetylacetonate) or when using other catalysts such as [Rh(CO)2(acac)], [Co2(CO)8], [Ir(cod)(acac)] (cod = 1,5cyclooctadiene), [Ru3(CO)12], [Fe3(CO)12], and [Ni(acac)2] (Table 1, entry 21). With the optimized reaction conditions established (Table 1, entry 20), we examined the scope and limitations of this aminocarbonylation process with respect to various olefins (Table 2). Both shortand long-chain terminal olefins 1a–1e provided the corresponding amides in good to excellent yields and with good regioselectivities (Table 2, entries 1–4). The more challenging internal olefin 1e was transformed to C9-amides in 53 % yield. The linear amide is still formed preferentially because of isomerization of the olefin (66:34 n/i selectivity; Table 2, entry 5). Lower linear [*] X. Fang, Dr. R. Jackstell, Prof. Dr. M. Beller Leibniz-Institut f r Katalyse e. V. an der Universit t Rostock Albert-Einstein-Strasse 29a, 18059 Rostock (Germany) E-mail: matthias.beller@catalysis.de Homepage: http://www.catalysis.de

Abstract: Palladium catalysis has been instrumental in the development of the intramolecular diamination of alkenes. Reagent combinations of a palladium catalyst and iodosobenzene diacetate or copper(II) salts, respectively, represent the broad applicability and mechanistic variation. Recent work has established alternative copper and bromine catalysts. The occupation with this reaction has also contributed to the development of high oxidation state metal catalysis in alkene difunctionalization and significantly broadened the spectrum of Pd-catalyzed C–N bond-forming reactions in general.

Abstract: A palladium-catalyzed 1,4-addition across the commodity chemical 1,3-butadiene to afford skipped polyene products is reported. Through a palladium σ → π → σ allyl isomerization, two new carbon–carbon bonds are formed with high regioselectivity and trans stereoselectivity of the newly formed alkene. The utility of this method is highlighted by the successful synthesis of the ripostatin A skipped triene core.

Abstract: Halogen and chalcogen cations (X+ = Br+, I+, ArS+, and ArSe+) were generated by low-temperature electrochemical oxidation in the presence of dimethyl sulfoxide (DMSO) and were accumulated in the so...

Abstract: The development of new catalytic systems for cis-dihydroxylation and epoxidation of alkenes, based on atom economic and environmentally friendly concepts, is a major contemporary challenge. In recent years, several systems based on manganese catalysts using H2O2 as the terminal oxidant have been developed. In this review, selected homogeneous manganese catalytic systems, including ‘ligand free’ and pyridyl amineligand based systems, that have been applied to alkene oxidation will be discussed with a strong focus on the mechanistic studies that have been carried out.

Abstract: Rather u(Ni)que: Two new C-H alkenylation reactions, that is C-H/C-O alkenylation and decarbonylative C-H alkenylation, of azoles are uniquely catalyzed by Ni/dcype. These azole alkenylation reactions are successfully applied to the convergent formal synthesis of siphonazole B.

Abstract: Assistance provided: The directing group in the title reaction not only activates the substrates but also allows the stereospecific formation of cis-trifluoromethylated products. The reaction is operationally simple and tolerates a wide variety of functional groups, thus providing an efficient method for the stereoselective synthesis of β-CF3 -functionalized acrylamide derivatives.

Abstract: Enamines and enamides are useful synthetic intermediates and common components of bioactive compounds. A new protocol for their direct synthesis by a net alkene C-H amination and allylic amination by using catalytic Cu(II) in the presence of MnO2 is reported. Reactions between N-aryl sulfonamides and vinyl arenes furnish enamides, allylic amines, indoles, benzothiazine dioxides, and dibenzazepines directly and efficiently. Control experiments further showed that MnO2 alone can promote the reaction in the absence of a copper salt, albeit with lower efficiency. Mechanistic probes support the involvement of nitrogen-radical intermediates. This method is ideal for the synthesis of enamides from 1,1-disubstituted vinyl arenes, which are uncommon substrates in existing oxidative amination protocols.

Abstract: The removal of two vicinal hydrogen atoms from an alkane to produce an alkene is a challenge for synthetic chemists. In nature, desaturases and acetylenases are adept at achieving this essential oxidative functionalization reaction, for example during the biosynthesis of unsaturated fatty acids, eicosanoids, gibberellins and carotenoids. Alkane-to-alkene conversion almost always involves one or more chemical intermediates in a multistep reaction pathway; these may be either isolable species (such as alcohols or alkyl halides) or reactive intermediates (such as carbocations, alkyl radicals, or σ-alkyl-metal species). Here we report a desaturation reaction of simple, unactivated alkanes that is mechanistically unique. We show that benzynes are capable of the concerted removal of two vicinal hydrogen atoms from a hydrocarbon. The discovery of this exothermic, net redox process was enabled by the simple thermal generation of reactive benzyne intermediates through the hexadehydro-Diels-Alder cycloisomerization reaction of triyne substrates. We are not aware of any single-step, bimolecular reaction in which two hydrogen atoms are simultaneously transferred from a saturated alkane. Computational studies indicate a preferred geometry with eclipsed vicinal C-H bonds in the alkane donor.

Abstract: A highly specific, distinct color change in the crystals of a metal–organic framework with pendant allyl thioether units in response to Pd species was discovered. The color change (from light yellow to orange/brick red) can be triggered by Pd species at concentrations of a few parts per million and points to the potential use of these crystals in colorimetric detection and quantification of Pd(II) ions. The swift color change is likely due to the combined effects of the multiple functions built into the porous framework: the carboxyl groups for bonding with Zn(II) ions to assemble the host network and the thioether and alkene functions for effective uptake of the Pd(II) analytes (e.g., via the alkene–Pd interaction). The resultant loading of Pd (and other noble metal) species into the porous solid also offers rich potential for catalysis applications, and the alkene side chains are amenable to wide-ranging chemical transformations (e.g., bromination and polymerization), enabling further functionalization ...

Abstract: Secondary interactions are demonstrated to direct the stability of well-defined Ru–NHC-based heterogeneous alkene metathesis catalysts. By providing key stabilization of the active sites, higher catalytic performance is achieved. Specifically, they can be described as interactions between the metal center (active site) and the surface functionality of the support, and they have been detected by surface-enhanced 1H–29Si NMR spectroscopy of the ligand and 31P solid-state NMR of the catalyst precursor. They are present only when the metal center is attached to the surface via a flexible linker (a propyl group), which allows the active site to either react with the substrate or relax, reversibly, to the surface, thus providing stability. In contrast, the use of a rigid linker (here mesitylphenyl) leads to a well-defined active site far away from the surface, stabilized only by a phosphine ligand which under reaction conditions leaves probably irreversibly, leading to faster decomposition and deactivation of t...