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The design and operation of a new kind of high pressure/high temperature stirred IR cell is described. The cell is a stand-alone autoclave made of Hastelloy and effective stirring and gas diffusion are provided by a magnetically driven Teflon shaft. The length of the optical path can be regulated without the need of calibrated spacers and the problem of the sealing of the windows to the cell body has been solved by employing FEP (fluorinated ethylene propylene) encapsulated Viton O- rings, which, upon adapting to the cell when warmed, provide an excellent seal that is also tolerant of all standard solvents. The use of this kind of O-rings allows taking advantage of the chemical resistance of Teflon without needing to mechanically stress the fragile windows as it would be required if bulk Teflon O-rings were employed.

The reductive cyclization of different organic nitro compounds by carbon monoxide, catalyzed by transition metal complexes, is a very efficient and clean strategy for the synthesis of many N-heterocycles. However, its use requires the use of autoclaves and pressurized CO lines. In this perspective, the authors will present the results obtained in their laboratories on the use of phenyl formate as a convenient CO surrogate, able to liberate carbon monoxide under the reaction conditions and allowing the use of a cheap glass pressure tube as a reaction vessel. In most cases, yields were better than those previously reported by the use of pressurized CO, proving that the use of CO surrogates can be a viable alternative to the gaseous reagent.

The first examples of heterogeneous Fe-catalysed cyclopropanation reactions are presented. Pyrolysis of in situ-generated iron/phenanthroline complexes in the presence of a carbonaceous material leads to specific supported nanosized iron particles, which are effective catalysts for carbene transfer reactions. Using olefins as substrates, cyclopropanes are obtained in high yields and moderate diastereoselectivities. The developed protocol is scalable and the activity of the recycled catalyst after deactivation can be effectively restored using an oxidative reactivation protocol under mild conditions.

In a recent paper on this Journal (J. Catal. 369 (2019) 257–266), we reported on the effect of ppm amounts of iron compounds on the palladium/iodide (and even palladium/chloride) catalytic system for the oxidative carbonylation of aniline to diphenylurea. In a “Polemic” against our work, Gabriele and coworkers argued against some of the conclusions we had drawn and even against our experimental practice. Here, we reply in detail to this polemic. Some of the content of the latter is due to some misunderstanding, whereas some assertions are untenable and in contrast with experimental data.

The palladium/iodide couple is the most investigated catalytic system for the oxidative carbonylation of amines to give ureas or carbamates. In reinvestigating it, we found that the most prominent role of iodide is to etch the stainless steel of the autoclave employed in most of previous works, releasing in solution small amounts of iron salts. The latter are much better promoters than iodide itself. Iron and iodide have a complex interplay and, depending on relative ratios, can even deactivate each other. The presence of a halide is beneficial, but chloride is better than iodide in this respect. The ideal Fe/Pd ratio is around 10, but even an equimolar amount of iron with respect to palladium (0.02 mol% with respect to aniline, corresponding to 12 ppm Fe with respect to the whole solution) is sufficient to boost the activity of the catalytic system. Such small amount may also come from Fe(CO)5 impurities present in the CO gas when stored in steel tanks. The role of the solvent has also been investigated. It was found that the reason for the better selectivity in some cases is at least in part due to a hydrolysis of the solvent itself, which removes the coproduced water.

A series of alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of substituted nitro compounds to afford heterocycles, especially indoles. Phenyl formate was found to be the most effective, allowing to obtain the desired products in excellent yields, often higher than those previously reported with pressurized CO. Detailed experiments and kinetic studies discern between a metal-catalyzed and a base-mediated activation of phenyl formate confirming that just the base is effective in catalyzing its decarbonylation.

Reactions of various substituted bis(imino)acenaphthenes (R-BIAN) with FeCl2(thf)1.5 afforded the tetrahedral complexes (R BIAN)FeCl2 (2) from bulky α-diimines and the octahedral complexes [Fe(R-BIAN)3][FeCl4]2 (3) from less bulky ligands. The driving force of the formation of complexes 3 is the high ligand-field stabilization of the low-spin Fe(II). The two sets of complexes exhibit distinct CT band intensities and redox activities. (R BIAN)FeCl2 complexes showed reversible ligand-centered reductions at -0.9 V (vs. FcH/FcH+); further reduction led to decomposition. Irreversible oxidations were observed at 0.2 and 0.4 V associated with a reduction at -0.4 V as well as a ligand-centered redox event at 1.0 V. First applications of the Fe(BIAN) complexes to hydrogenations of alkenes documented good catalytic activity under mild conditions.

Ar-BIANs and related α-diimine Co complexes were wet impregnated onto Vulcan® XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800 °C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110 °C, 50 bar H 2 ) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen.

In the presence of carbon monoxide, the palladium/phenanthroline system catalyzes the intramolecular amination of thiophene rings following the reduction of a nitroalkene moiety directly attached to the S-heterocyclic ring. Optimization of the ligand and reaction conditions allowed the synthesis of a series of thienopyrroles aryl/alkyl-substituted at either the 2- or 3-position of the pyrrole ring. By using low pressures of carbon monoxide (5 bars), high yields of fused bicyclic compounds have been obtained (up to 98 % yield).

Use of homogeneous catalysts poses the problem of their recovery at the end of the reaction. A possible strategy to circumvent this problem is to make the ligand part of a polymer with limited solubility. In this work, we investigated the immobilization of complexes of Ar-BIAN ligands (Ar-BIAN = bis(arylimido)acenaphthene). We employed 4,4′-methylene-bis(aniline) as an amine able to bridge two acenaphthene moieties. However, the obtained product was a mixture of short-chain oligomers. A ruthenium complex of this mixture (Oligo-BIAN) was indeed catalytically active in the model hydrogenation of nitrobenzene to aniline by CO/H2O but the complexes were too soluble in the reaction mixture to allow for an easy recovery. We thus further extended the molecular weight of Oligo-BIAN by polymerizing it with terephthaloyl chloride obtaining a polyamide (Poly-BIAN). The latter was insoluble in all solvents but its ruthenium complex was catalytically inactive in the model reaction. An deeper investigation, showed that coordination mode of monomeric Ar-BIAN ligands and Oligo-BIAN to [Ru(CO)3Cl2(THF)] is differs from that of Poly-BIAN. This result was completely unexpected and constitutes a general warning not to give for granted the coordination mode of a complex to a functionalized polymer.

Novel unsaturated C10 diesters are produced via the alkoxycarbonylation of δ-lactone 1 (3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one), derived from the telomerization of CO2 and butadiene. The key for the selective valorization of 1 is the use of a catalytic system based on PdCl2, a chelating phosphine bearing electron-withdrawing groups and an acidic promoter. The unsaturated C10 methyl diester can be easily hydrogenated on Pd/C under mild conditions to afford its corresponding saturated diester. Subsequent hydrogenation using the homogeneous [Ru(acac)3]/Triphos catalysts gives 2-ethyloctane-1,8-diol in high yield. The overall procedure allows synthesizing new building blocks for the manufacturing of renewable polymers and polymer processing materials.

1,10-Phenanthrolines are widely employed as ligands, but their use on a large scale is constrained by their difficult purification, which usually requires lengthy chromatographic separations. Herein, we describe a purification strategy that takes advantage of the high stability and low solubility of phenanthroline complexes to separate them from the by products of their synthesis. The formation of ZnCl2 complexes was employed, from which the free ligand can be recovered by reaction with aqueous NH3 in a biphasic CH2Cl2/H2O system. The same strategy was also successfully employed to purify related quinolino-guanidine ligands, demonstrating that the procedure is of general applicability.

An improved hydrogenation of nitroarenes using nano-structured iron- and cobalt-based catalysts is presented. Modifications of the heterogeneous catalysts by N-doped graphene-flakes are crucial for the success of selective reductions. The use of polar solvents and basic additives has a significant positive influence on the rate of reduction of nitroarenes. This allows performing non-noble metal-catalysed hydrogenations under very mild reaction conditions (e.g. 70 °C and 20 bar). On the basis of the obtained catalytic results a heterolytic mechanism for the hydrogenation process is postulated, too.

The novel class of bis-arylaminoacenaphthylenes (Ar-BIANH2) was employed for the preparation of zirconium and yttrium complexes to be used as catalysts for cyclohydroamination of a number of primary and secondary aminoalkenes. The complex [(2,6-iPr2C6H3-BIAN)Zr(NMe2)2(Z1-NHMe2)] was isolated and completely characterized, including X-ray diffraction analysis. Despite its easy and almost quantitative isolation, it showed only moderate catalytic performance in the intramolecular hydroamination, irrespective of the cyclization precursor used. On the other hand, in situ generated YIII complexes obtained using the same class of ligands were found to be very active, leading to the hydroamination of substrates including those normally reluctant in undergoing cyclization such as those featuring an internal non-activated CQC double bond. Electron donating substituents and especially steric hindrance on the ligand improve the performance of the catalysts, allowing us to decrease the catalyst loading to 1 mol% in the latter case.

An efficient catalytic cyclization of β-nitrostyrenes to indoles was developed. The reaction was applied to the synthesis of 3-arylindoles and 2-alkylindoles. Given that in the latter case the starting β-nitrostyrenes can be easily obtained by a Henry reaction, the present method allows indoles to be obtained in a two-step sequence starting from cheap reactants.

An unprecedented reactivity of aryl azides toward alkynes is presented herein. The reaction performed well in the presence of 2 mol % of ruthenium porphyrin catalysts and afforded substituted indoles instead of triazoles. The procedure is particularly appealing for the synthesis of C3-functionalized indoles which bear EWG on the fragment coming from the azide. The method allowed the synthesis of 15 derivatives with yields up to 95%, high regioselectivity, and without requiring the time-consuming prefunctionalization of reagents and the addition of oxidants and/or additives.

The article describes the organizational model of the social and health services chosen by Marche Region both at regional and local level. At regional level the planning function prevails, while locally the prevailing function is based on management. The article also gives an analysis of the implementation state of the social-health integration’s regional system.

A new nonsymmetric bis(aryl-imino)acenaphthene (Ar-BIAN) ligand, featured by a subtle steric and electronic unbalance of the N-donor atoms, is reported. With the new ligand and the corresponding symmetrically substituted derivatives, both neutral and monocationic PdCH3 compounds have been synthesized and characterized. The series of the monocationic complexes [Pd(CH3)(L)(Ar-BIAN)][PF6] (L=CH3CN, dmso) has been extended to dimethyl sulfoxide derivatives. The monocationic complexes are tested as precatalysts for the ethylene/methyl acrylate cooligomerization under mild reaction conditions of temperature and ethylene pressure. The catalytic product is a mixture of ethylene/acrylate cooligomers and higher alkenes. The catalysts containing the new nonsymmetric ligand are found to be more productive than those with the symmetric Ar-BIANs. The Pd–dmso catalysts are more productive and show a longer lifetime than their Pd–NCCH3 counterparts.

New copper complexes of several thiosemicarbazones have been prepared and characterized. All complexes have been prepared by employing Cu (II) acetate hydrate, but analytical and spectroscopical data for the isolated complexes revealed that in most cases a reduction to copper (I) occurred. Cyclopropanation reactions of several olefins by ethyldiazoacetate (EDA) in the presence of catalytic amounts of the complexes were examined. The reported results showed that all complexes are competent catalysts for the cyclopropanation reaction of unactivated olefins. Cyclopropanes were obtained in high yields (up to 97%, TON up to 18,400) with moderate to excellent diastereoselectivities (up to >99%).

Shedding light on azides: [Ru(TPP)CO] (TPP=tetraphenyl porphyrin dianion), white light and O(2) were found to be a suitable catalyst combination to perform the annulation of several biaryl azides. The high chemoselectivity of the process allows the synthesis of phenanthridines and dihydrophenanthridines in good yield and purity.

This paper describes the synthesis of allylic amines by aryl azides (ArN3) catalysed by [Ru(TPP)CO] (TPP = dianion of tetraphenylporphyrin). The employment of aryl azides renders the methodology sustainable as the formation of molecular nitrogen is the only stoichiometric byproduct. The isolation of catalytic intermediates and spectroscopic and kinetic studies revealed interesting information about the reaction mechanism, which could improve its catalytic efficiency in future research. An important result is the X-ray characterisation of [Ru(TPP)(ArN)2] [Ar = 3,5-(CF3)2C6H3], which is active in both stoichiometric and catalytic nitrene transfer reactions. The proposed involvement of carbonyl-monoimido-ruthenium porphyrin complexes in the catalytic cycle is also derived from our kinetic and experimental results. All the data indicate the coexistence of two mechanisms, where the electronic nature of the engaged aryl azide and olefin concentration determine one mechanism or the other.

The synthesis and characterization of copper(I) complexes of the novel pyridine-containing macrocyclic ligand (PC-L) and their use as catalysts in the Henry reaction are reported. The pyridine-based 12-membered tetraaza macrocyclic (PC-L) ligand 1 can be obtained in good overall yield (85%) from commercially available starting materials. The Cu(I) complexes showed good catalytic activities in the Henry reaction of different aldehydes and nitroalkanes. Remarkable diastereoselectivity was observed when isatine was reacted with nitroethane under catalytic conditions. Copyright © 2011 John Wiley & Sons, Ltd.

A review of synthetic methodologies reported in the last five years that yield N-heterocyclic products by intramolecular cyclization of organic azides with a particular emphasis on transformations catalyzed by metal complexes is presented. These reactions have been classified according to the ring size of the formed heterocycle.

We report herein the synthesis of the porphyrins 5,10,15,20-tetrakis(4-carboxybiphenyl)-porphyrin (H2TCBP) and 5,10,15,20-tetrakis(4-carboxy-2,6-dimethylbiphenyl)porphyrin (H2TCDMBP) bearing diphenyl units on meso-positions, and of their cobalt and silver derivatives. The silver complexes of H2TCDMBP and of H2TCPP ( H2TCPP = 5 ,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) were investigated by X-ray crystallography and their supramolecular organization elucidated. Co(TCBP) was reacted with copper formate, yielding a polymeric compound that showed a catalytic activity in the benzylic amination of hydrocarbons using arylazide as aminating agent.

Benzylic amines are synthesized in yield up to 90% by the Ru(TPP)CO -catalyzed amination of both exocyclic and endocyclic benzylic C-H bonds. The choice of arylazides as nitrogen sources confers to the methodology a good sustainability due to the formation of molecular nitrogen as the only stoichiometric by-product. A preliminary mechanistic investigation evidenced a critical role of the hydrocarbon concentration to drive the chemoselectivity of the reaction.

Polymeric membranes embedding a metal complex have been previously employed as reusable catalysts under relatively mild conditions. Herein, the first example of a polymeric catalytic membrane employed under very forcing conditions (160 °C and 5 MPa CO) is reported. The reaction investigated was the reduction of nitrobenzene to aniline by CO/H 2 O, catalyzed by ruthenium bis(arylimino)acenaphthene (Ar-BIAN) complexes. To better retain the complex in the membrane, a modified ligand, with long alkyl chains in the para positions of the aryl rings, was prepared. Among several polymers tested as membranes, PEEK-WC, a modified polyether ether ketone, gave the best results. Attempts to embed the ligand only in the membrane and functionalize it with the metal later, analogously to the in situ generation of the active species practiced for the homogeneous system, failed and it was necessary to synthesize new complexes that could be reduced under the reaction conditions. Best results were obtained using [Ru(Ar-BIAN)(CO) 2 Cl 2 ] + Et 3 N. During the reaction, the complex is transformed into a mixture of [Ru 3 (CO) 12 ] and a reduced form of the ligand, Ar-BIANH 2 . The latter was independently prepared and shown to be able to reduce nitrobenzene even in the absence of any metal. A new kind of support was designed to allow the placing of the membrane in a stirred autoclave. Using only water as solvent, no metal or ligand leaching was detected and several recycles were performed. All employed membranes were thoroughly characterized by different techniques.

Inspired by the results of a previous mechanistic study, a series of mostly new nonsymmetric phenanthrolines were synthesized and tested as ligands in the palladium-catalyzed reductive carbonylation reaction of nitrobenzene to methyl phenylcarbamate. Very good results were obtained when the asymmetry was of an electronic nature (a donating substituent in the para position of one of the two pyridinic rings and an electron-withdrawing or no substituent on the para position of the other pyridinic ring), but steric hindrance in the ortho or meta position retarded the reaction. The TOF for the modified system is the highest ever reported for any carbonylation reaction of nitroarenes.

In this paper we report the preparation of catalytic polymeric membranes having the complex [( N,N ′- bis (3- tert -butyl-5-(heptadecafluorooctyl)salicylidene)- trans -1,2-cyclohexanediamine)Co] embedded into Hyflon AD60X, PES and PSf and their use in the cyclopropanation reaction of olefins with ethyl diazoacetate (EDA). A study of the reaction in the homogeneous phase was also performed. The kinetics of the cyclopropanation reaction is first-order in the diazoacetate and the catalyst and zero order in the olefin, but we observed a more complex dependence on the additive, NMI ( N -methylimidazole). The positive effect of the additive is completely reversed at NMI concentration higher than 6·10 −2 M.

The addition of Ru3(CO)12, dimethyl carbonate, or both to the reaction mixture improves the selectivity of the palladium/phenanthroline-catalyzed reaction of nitroarenes, arylalkynes, and CO to give 3-arylindoles. When 4-fluorophenylacetylene and nitrobenzene are used as substrates, the indole skeleton of Fluvastatin and other pharmaceutically active compounds is obtained in one step.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Herein we report the one-pot synthesis of several N-heterocyclic compounds by rearrangement reactions of N-aryl-2-vinylaziridines. The optimization of the synthetic methodology employed allowed us to obtain differently substituted 2,5-dihydro-1H-benzo[b]azepines in good yields and purities. The relationship between the nature of the starting N-aryl-2-vinylaziridine and the obtained N-heterocycle was also investigated. Finally, to rationalize all the experimental results reported in this paper a theoretical study was performed that casts light on the reaction mechanism.

Cobalt(II) complexes of chiral bis-binaphthyl porphyrins were prepared, and their catalytic activity in the asymmetric cyclopropanation of alkenes with ethyl diazoacetate was examined. Good yields and enantioselectivities (up to 90% ee) were observed with cis/trans ratios reaching 11:89. UV−vis and 1H NMR studies suggest that the axial nitrogen ligand N-methylimidazole could play a role in changing the enantioselectivity of the reaction.

In this paper we report the preparation of catalytic membranes having the complex Ru(4-(CF3)TPP)CO (1) (TPP = dianion of tetraphenylporphyrin) embedded in the perfluorinated polymer Hyflon AD60X and their use in the aziridination reaction of olefins by aryl azides. The heterogeneous membrane catalysts afforded high selectivities in aziridine (90–99%). In several cases the membrane was reused three times with a catalyst leaching ≤6% but no decrease in selectivities upon recycle was observed.

The optimized conditions are applied to the preparation of a series of 2- or 3-substituted indole structures bearing additional functions at the arene part.

This article describes the progress made in the field of reductive carbonylation of nitroarenes to give isocyanates, carbamates, and ureas. Isocyanates are intermediates in the production of many chemicals among which are polyurethanes. Carbamates and urea are of interest themselves, but can also be thermally cracked to afford the corresponding isocyanates. However, the techniques employable for this thermolysis step are not discussed here. The most effective catalytic systems are all homogeneous and based on palladium, rhodium, or ruthenium complexes or on selenium compounds. This article includes all significant contributions from the early reports in the 1960 to October 2015. More attention is given to the systems which are more promising in view of an industrial application. Several mechanistic studies are also considered in a critical manner.

Aryl azides have been used as atom-efficient nitrene transfer reagents in the (porphyrin)ruthenium-catalyzed amination of olefins. Several azides, olefins and [Ru(porphyrin)CO] complexes were tested to investigate the scope and limits of the reaction. Quantitative yields and short reaction times were achieved by using terminal olefins and aryl azides bearing electron-withdrawing groups on the aryl moiety. The reactions were influenced by steric factors. Internally disubstituted olefins exhibited a lower reactivity and tri- and tetrasubstituted olefins did not react at all. A very high turnover number (TON) for the [Ru(TPP)CO] (TPP = tetraphenylporphyrin dianion) catalyzed amination of α-methylstyrene by p-nitrophenyl azide was obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

[Ru(CO)(porphyrin)] complexes have been found to catalyze the direct aziridination of conjugated dienes by aryl azides with high chemoselectivity, to provide N-aryl-2-vinylaziridines. To determine the scope of the reaction, several hydrocarbons and azides were tested. The reactions between 2,3-dimethylbuta-1,3-diene and aryl azides bearing electron-withdrawing groups in the para or meta positions in their aryl moieties occur very efficiently in short times, while the selectivities of the aziridinations are governed by the steric hindrances of the double bonds, so lower yields are registered with sterically encumbered 1,4-disubstituted dienes, though it is worth noting that the aziridination of trans,trans-1,4-diphenylbuta-1,3-diene was stereospecific and that only one isomer was obtained. The aza-[3,3]-Claisen rearrangement of 2-isopropenyl-2-methyl-N-(4-nitrophenyl)aziridine to produce the corresponding 2,5-1H-benzo[b]azepine is also reported.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Fluorides promote the palladium–phenanthroline catalyzed carbonylation of nitroarenes to carbamates. The effect is more evident on the rate of the reaction at short reaction times, but a positive effect on selectivity is also observed under certain conditions. The effect is observed even under conditions under which chloride inhibits the reaction. Tetraethylammonium is a better countercation than sodium. Copyright © 2007 John Wiley & Sons, Ltd.

The interaction of organic azides with transition metal complexes will be discussed with particular attention to the coordination modes of these molecules. The stoichiometric reactions of organic azides with coordinated ligands will be considered and their use in amination reactions catalyzed by transition metal complexes will be discussed in detail. The utility of these catalytic reactions for the synthesis of organic compounds will be stressed.

We report here the syntheses of two new metal complexes (M = Co, 2; M = Ru, 3) of the chiral porphyrin TmyrtP (1) (TmyrtP = dianion of the meso-tetrakis[(1R)-apopinen-2-yl]porphyrin). Both complexes exist as a mixture of atropisomers. Complexes 2 and 3 activate aromatic azides for the amination under mild conditions of unsaturated hydrocarbons. Even though the observed ee values are low, this is the first asymmetric transfer of the nitrene residue of aryl azides to a prochiral olefin catalyzed by a transition metal complex to be reported in the literature. Complex 3 also showed a good catalytic activity in cyclopropanation reactions with ethyldiazoacetate even at low temperatures (−30 °C) but a poor diastereo- and enantioselectivity were observed.