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Due to the generation of multiple intermediates during the nitroarene reduction, precise interception of single one to develop tandem reactions involving both C−C and C−N bond formations still remains a significant challenge. Herein, the relay catalysis of a supported bifunctional cobalt catalyst with l‐proline has been successfully applied to establish a bran‐new reductive annulation reaction of nitroarenes and formaldehyde, which enables direct and diverse construction of both symmetrical and unsymmetrical 1,3‐diaryl imidazolines. It proceeds with operational simplicity, good substrate and functionality compatibility, and excellent step and atom‐efficiency. Mechanistic studies reveal that the Co‐catalyst exhibits a synergistic effect on the formation of key N‐hydroxy imine, and the l‐proline subsequently facilitates the key C−C bond formation. The current work opens a door to develop useful transformations with nitroarenes by reduction‐interrupted strategy. [ABSTRACT FROM AUTHOR]

We report the C−H alkylation of biarylphosphines at the ortho′ position(s) with alkenes by using rhodium(I) catalysis, which provides straightforward access to a large library of multifunctionalized phosphines. Some of these modified ligands outperformed commercially available phosphines in the Pd‐catalyzed carboxylation of aryl bromides with carbon dioxide in the presence of a photoredox catalyst. [ABSTRACT FROM AUTHOR]

Azaspiro[4.5]trienones bearing ketone side chains at the 3‐position are prepared from N‐alkyl‐arylpropiolamides and ketones via oxidative 1,2‐difunctionalization of alkynes. The cascade sequence starts with the generation of alkenyl peroxide intermediates, which are obtained by addition of tert‐butyl hydroperoxide to ketones in presence of a catalytic amount of a strong acid. Then, the ketone radical adds to alkynes, followed by spirocyclization and dearomatization process. This method represents a new example of difunctionalization of alkynes with simultaneous formation of two carbon−carbon single bonds and one carbon−oxygen double bond in one step. [ABSTRACT FROM AUTHOR]

An efficient approach for the fast modification of arylphosphine oxides involving ruthenium(II)-catalyzed C−H bond alkylation with functional alkenes versus alkenylation has been developed depending on the acidic reaction conditions. Using this methodology, a few examples of desymmetrization of diarylphosphine oxides has allowed the formation of phosphorus derivatives containing three different substituents. After reduction of the phosphine oxide, this method allows the formation of aryl phosphines bearing a flexible pendent carboxylate. [ABSTRACT FROM AUTHOR]

A copper-catalyzed oxidative C(sp3)−H/N−H coupling of NH-heterocycles with affordable (cyclo)alkanes has been developed. This procedure involves C(sp3)−N bond formation through a radical pathway generated by homolytic cleavage of di- tert-butyl peroxide and trapping of the radical(s) by copper catalysts. The reaction tolerates a series of functional groups, such as bromo, fluoro, ester, ketone, nitrile, methyl, and methoxy. free-NH-containing indoles, pyrroles, pyrazoles, indazoles, and benzotriazoles are successfully N-alkylated. [ABSTRACT FROM AUTHOR]

A triflamide-tethered N-heterocyclic carbene (NHC)-bound RhI dicarbonyl catalyst was highly effective for both intermolecular hydroalkoxylation and intramolecular heteroannulation reactions. The involvement of both the amido nitrogen and triflato oxygen atoms of the triflamide functionality for alcohol activation and 1,2-hydrogen shift, respectively, was proposed. [ABSTRACT FROM AUTHOR]

Esters are important chemicals widely used in various areas, and alkoxycarbonylation represents one of the most powerful tools for their synthesis. In this communication, a new copper-catalyzed carbonylative procedure for the synthesis of aliphatic esters from cycloalkanes and alcohols was developed. Through direct activation of the C [ABSTRACT FROM AUTHOR]

Pyrrole- and indole-fused isocoumarins constitute important structural units in natural products and pharmacophores, although the direct and selective bifunctionalization of pyrrole and indole remain a challenge. Herein, we report a one-pot synthesis of pyrrole- and indole-fused isocoumarins from simple 1-methylpyrrole-2-carboxylic acid and 1-methylindole-3-carboxylic acid by annulation with alkynes in the presence of a ruthenium(II) catalyst based on [RuCl2( p-cymene)]2 with Cu(OAc)2 ⋅H2O as the oxidant in DMF. This ruthenium(II)-catalyzed transformation was shown to be profitably performed in water as the solvent. The reaction, which involves carboxylate coordination, activation of the heterocyclic sp2 C−H bond, and insertion of the alkyne, is regioselective, which leads to good yields of the isocoumarins. [ABSTRACT FROM AUTHOR]

The palladium-catalysed C−C bond formation via direct arylation of free-amine-substituted polyfluoroaniline derivatives proceeds in moderate to high yields with a variety of aryl bromides. The nature of the base was found to be crucial to promote the direct arylation with inhibition of the amination reaction. [ABSTRACT FROM AUTHOR]

Selective monoarylation of aryl 2-pyridyl ketones with a variety of arylbromides via arene sp2 CH bond activation/functionalisation is achieved with a [RuCl2( p-cymene)]2/ p-CF3C6H4CO2H catalytic system. The reaction via a 6-membered ruthenacycle is more difficult to perform than via a 5-membered cyclometallate but the activation of only one ortho CH bond is unprecedentedly highly selective. A variety of functional 2-pyridine derivatives are easily obtained. It is shown via H/D exchange that the carboxylic acid favours the reversible CH bond activation. [ABSTRACT FROM AUTHOR]

The palladium-catalysed dehydrogenation of sp3 carbon-hydrogen bonds of N-alkylbenzenesulfonamides allows a simple access to N-alkenylbenzenesulfonamides. The reaction proceeds with easily accessible catalysts, with pivalate as a base, and allows a variety of substituents both on nitrogen and on the arene moiety. [ABSTRACT FROM AUTHOR]

An efficient method for the preparation of new α-CF3 α-amino acid 1,7-enynes that contain electron-donating and electron-withdrawing groups on the triple bond has been developed that proceeds through a Sonogashira-type coupling reaction. The ring-closing enyne methathesis (RCEYM) of the obtained 1,7-enynes with commercially available Grubbs and Hoveyda catalysts provides access to a series of new cyclic α-amino acids. The latter compounds that contain the 1,3-diene moiety are attractive building blocks for the construction of trifluoromethylated polycyclic systems. [ABSTRACT FROM AUTHOR]

The Pd-catalysed direct arylation of heteroarene CH bonds by 2- or 4-bromobenzamides has been achieved. In the presence of KOAc as the base, no CN bond formation or CC coupling of two bromobenzamides was observed. Both primary and tertiary amides can be employed for CC cross-coupling of 4-bromobenzamides with a variety of heteroarenes to give the C5-arylated heteroarenes in good yields by using a low loading (0.5 mol %) of Pd(OAc)2 catalyst. However, no coupling product was observed with 2-bromobenzamide, and a moderate reactivity of 2-bromo- N, N-diethylbenzamide has been observed with 2 mol % PdCl(C3H5)(dppb) (dppb=1,4-bis(diphenylphosphino)butane) as the catalyst. A moderate influence due to the nature of the heteroarene was observed, and thiazoles, thiophenes, furans and pyrroles have been arylated successfully. The reaction of a thiazole with 2-bromo- N-phenylbenzamide led to a six-membered ring product by intramolecular cyclisation, whereas a 2-bromo- N-benzylbenzamide gave the desired intermolecular coupling product. [ABSTRACT FROM AUTHOR]

The activation of the CH bond of 1-phenylpyrazole ( 2) and 2-phenyl-2-oxazoline ( 3) by [Ru(OAc)2( p-cymene)] is an autocatalytic process catalyzed by the co-product HOAc. The reactions are indeed faster in the presence of acetic acid and water but slower in the presence of a base K2CO3. A reactivity order is established in the absence of additives: 2-phenylpyridine>2-phenyl-2-oxazoline>1-phenylpyrazole (at RT). The accelerating effect of added acetate ions reveals an intermolecular deprotonation after CH bond activation by a cationic RuII center (SE3 mechanism). The reactions of 1-phenylpyrazole and 2-phenyl-2-oxazoline first lead to the neutral cyclometalated complexes A2 and A3 ligated by one acetate. The latter dissociate to the cationic complexes B2 + and B3 +, respectively, and acetate. A slow incorporation of one or two D atoms into 2, 3, and 2-phenylpyridine ( 1) was observed in the presence of deuterated acetic acid. The 'reversibility' of the CH bond activation/deprotonation takes place from the cationic complexes B n + ( n=1-3). They are also involved in oxidative additions to PhI, which are rate-determining and lead to the mono- and bis-phenylated products at high temperatures. A general mechanism is proposed for the arylation of arenes 1-3 catalyzed by [Ru(OAc)2( p-cymene)]. In contrast, the reaction of Pd(OAc)2 with 2-phenylpyridine ( 1), is much faster: Pd(OAc)2>[Ru(OAc)2( p-cymene)]. Since the kinetics is not affected by added acetates, the reaction proceeds through a CMD mechanism assisted by a ligated acetate (intramolecular process) and is irreversible. A bis-cyclometalated PdII^PdII dimer D′1 is formed whose bielectronic electrochemical oxidation leads to a [PdIII^PdIII]2+ dimer, in agreement with the result of a reported chemical oxidation used in arene functionalizations catalyzed by Pd(OAc)2. [ABSTRACT FROM AUTHOR]

Two strong arms to hold the catalyst: (O,O) and (O,N) ‐ chelate ruthENium(II) complexes obtained from kojic acid or glycine are efficiENt catalysts for the (hetero)arylation of C sp 2H bonds if associated to potassium pivalate. Moreover, the catalysts operate in water. [ABSTRACT FROM AUTHOR]

The article offers information on the hydrogenation of aliphatic nitriles into primary amines by using ruthenium-benzylidenes and ruthenium-indenylidenes which catalysts. It informs that in many cases reduction is performed in presence of ammonia or ammonium salts to avoid the formation of secondary and tertiary amines. It also informs that olefin metathesis represents one of the most powerful transformations in chemical synthesis.

The reaction of 1,6- and 1,7-enynes, derived from carboxylic and boronic amino acids, with diazo compounds in the presence of the (cyclooctadiene)(pentamethylcyclopentadiene)ruthenium chloride complex [RuCl(cod)(C5Me5)] catalyst leads to the formation of strained bicyclic proline or homoproline derivatives in good yields. This catalytic transformation proceeds under mild conditions, in one step from easily accessible enynes and was applied to various protecting groups. High stereoselectivities for the created alkenyl chain and excellent diastereoselectivities for proline derivatives were obtained. [ABSTRACT FROM AUTHOR]

2-(Arylidene)cyanomethylbenzoxazoles have been prepared in water from benzoxazole-2-ylacetonitriles. Using multi-component reactions, a variety of heterocycles containing benzoxazole and nitrile functionality has been prepared. J. Heterocyclic Chem., (2011). [ABSTRACT FROM AUTHOR]