Since the rediscovery of proline in 2000 as catalyst aldol reaction by List, Barbas and Lerner and, soon after, development iminium catalysis D. W. C. MacMillan, emergence organocatalysis an important tool organic synthesis is outstanding. During last years, several research groups have worked new powerful methodologies that allow us to build difficult molecules with high yields enantioselectivities a metal-free environment. Moreover, possibility join two or more organocatalytic reactions...

A new pentamethylcyclopentadienyl-functionalized N-heterocyclic carbene ligand (Cp*-NHCMe) has been prepared and coordinated to iridium upon reaction with [Ir(μ-Cl)(cod)]2. The chiral Ir complex is obtained as a racemic mixture of the two possible enantiomers, its crystal structure described. compound shows high catalytic activity toward transfer hydrogenation, β-alkylation secondary alcohols primary alcohols, amination alcohols.

A series of five different "(p-cymene)Ru(NHC)" complexes (NHC = imidazolin-2-ylidene, imidazolin-4-ylidene, and pyrazolin-3-ylidene) have been obtained fully characterized. The crystal structure two the new has determined by X-ray diffraction methods. All tested in catalytic β-alkylation secondary alcohols with primary dimerization phenylacetylene, showing an excellent activity both processes. clear improvement on is observed when more basic NHC ligands are used. pyrazolylidene-Ru complex...

The use of the ligand triazolediylidene (ditz), has afforded preparation two new complexes Ru in which is bridging metal fragments a facially opposed (Janus-head) disposition. One dinuclear (2) and other tetranuclear (3). compound displays interesting structural features, as shown by X-ray diffraction studies. have been tested catalytic β-alkylation secondary alcohols with primary alcohols, providing high activities when both aliphatic aromatic are used.

A ferrocenyl–imidazolium salt can be employed as a precursor to stable [IrIII(H)(biscarbene)] complex (see X-ray crystal structure) under very mild conditions. The study shows that the role of base in activation imidazolium may not just simple deprotonation precursor.

The preparation of a new bis(dichloroimidazolylidene) ligand has provided chelate-N-heterocyclic complexes Rh(I) and Ir(I), which have been fully characterized. crystal structures three the are described. study electronic properties ligands was made on basis ν(CO) stretching frequencies carbonyl derivatives, showing that chloroimidazolylidene is significantly less σ-donating than related nonchlorinated analogue. This modification important implications for catalytic compounds obtained, as...

A series of bis-N-heterocyclic carbenes rhodium and iridium have been obtained characterized. The formation the M−C bond has studied according to experimental theoretical data, showing that two different mechanisms are operative for first (single proton deprotonation bisimidazolium salt, or oxidative addition followed by metal hydride) second (oxidative C−H bond, yielding a NHC-IrIII-H species) metalation processes. In case complexes with long linkers between imidazolium rings, reductive...

The metalation of a series C2-Me-substituted monoimidazolium and bisimidazolium salts to [Cp*IrCl2]2 is described. reaction the salt provides species Cp*Ir(aNHC)Cl2, in which NHC shows an abnormal coordination mode. use different patterns depending on linker length between two azolium rings. For methylene-linked salt, only compound obtained unusual type chelating ligand coordinated through methylene group resulting from CH activation C2-Me group. ethylene-linked similar product obtained,...

A new pyridine-4,5-dichloroimidazol-2-ylidene complex of Ir(I) has been obtained, and its catalytic activity toward hydrosilylation phenylacetylene 4-aminophenylacetylene studied. The addition HSiMe2Ph to the latter species afforded corresponding IrIII-NHC hydrosilylated species, whose molecular structure was determined. This nonchlorinated analogue have used as catalyst a series reactions designed for elucidating processes. mechanism studied by means electrospray ionization mass...

Graphical Abstract This is the cup of a chemist: Organocatalytic intermolecular α-alkylation has been accomplished. The groups Melchiorre and Cozzi have recently reported realization this long-time goal in organocatalysis, by crucial use stabilized carbocations. Alkylated products are obtained good yields with moderate to enantioselectivities.

The reasons for the efficiency of silver oxide route in synthesis Ag(I) N-heterocyclic carbene complexes have been investigated by means DFT calculations. A general reaction system that incorporates two N,N-dimethyl imidazolium cations, iodides as counterions, Ag2O, and dichloromethane solvent was considered. Exploration several pathways formation silver−NHC cations gives a clear picture mechanism. favored involves barrierless very exergonic deprotonation first followed low barrier also...

Abstract High molecular weight polypropylene carbonates were prepared by CO 2 /propylene oxide copolymerization catalyzed salcy‐naphthalene cobalt complexes. The introduction of methyl groups in the ortho position naphthalene‐based salcy ligands and catalyst loading presence hexane as a co‐solvent crucial to enhance catalytic performance for production polycarbonates high weight.

Ein Ferrocenyl-Imidazolium-Salz fungiert bei sehr milden Bedingungen als Vorstufe für einen stabilen [IrIII(H)(biscarben)]-Komplex (siehe Strukturbild). Die Untersuchung ergab, dass die Rolle der Base Aktivierung des Imidazoliumsalzes über eine einfache Deprotonierung hinausgehen könnte.

Low-density (LD) and high-density polyethylene (HDPE), recycled or not, incorporates up to 7 wt% of ester groups after reacting either with ethyl diazoacetate (EDA) under catalytic solvent free-reaction conditions, maleic anhydride (MA) acrylates (AC) radical conditions. The resulting upcycled esters are hydrolytically stable at extreme pH (0-14) can be further transformed into carboxylic acids, carboxylates, other amides.

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at glance that was extracted from about 200 leading journals. To access of an article which published elsewhere, please select “Full Text” option. The original trackable via the “References”

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at glance that was extracted from about 100 leading journals. To access of an article which published elsewhere, please select “Full Text” option. The original trackable via the “References”

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at glance that was extracted from about 100 leading journals. To access of an article which published elsewhere, please select “Full Text” option. The original trackable via the “References”