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We herein report the synthesis and catalytic application of a new family of dinuclear Cu(I) complexes based on [N,P]-pyrrole ligands. The Cu(I) complexes (4a–d) were obtained in good yields and their catalytic properties were evaluated in the1,3-dipolar cycloaddition of azomethine ylides and electron-deficient alkenes. The air-stable complexes 4a–d exhibited high endo-diasteroselectivity to obtain substituted pyrrolidines, and the catalytic system showed excellent reactivity and wide substitution tolerance. [ABSTRACT FROM AUTHOR]

The synthesis of a series of ferrocenylvinylketenes as stable η4-[Fe(CO)3] complexes (3a–f) was successfully accomplished through the reaction of η2-[Fe(CO)4] complexes under mild carbonylation conditions. The reactivity of 3a–f under thermal conditions afforded the unexpected formation of a novel family of (μ2,η3-allyl-η5-oxapentadienyl)diiron pentacarbonyl complexes 5a–f proposed to be formed by a sequence metathesis-haptotropic rearrangement between the starting η4-vinylketene iron(0) complex 3 and a η4-vinylcarbene iron(0) complex trapped in situ after a reversible carbonylation process favored by the thermal conditions. An electron density distribution analysis (EDD) of 5e using high-resolution X-ray diffraction data in combination with the DFT framework was performed to understand the electronic communication between the two iron fragments. [ABSTRACT FROM AUTHOR]

The double addition of bis(trimethylsilyl) ketene acetals (1a-1b, [R.sub.1] = C[H.sub.3], -[(C[H.sub.2]).sub.5]-) to 2- substituted pyrazines promoted by triflic anhydride leads to γ-lactones in a single step. A systematic study involving electron- withdrawing and electron-donating groups ([R.sub.2] = CN, COOMe, PhCH = CH, Cl, Me, OMe) in the pyrazine ring reveals a strong dependence of electronic effects on the regiochemistry of nucleophilic addition. Key words: pyrazines, γ-lactones, N-activation. La double addition des acetals de bis (trimethylsilyl) cetenes (1a-1b, [R.sub.1] = C[H.sub.3], -[(C[H.sub.2]).sub.5]-) sur les pyrazines substituees en 2 et activees par l'anhydride triflique conduit a la formation de γ-lactones en une seule etape. Une etude systematique utilisant des substituants electro-attracteurs et des electro-donneurs ([R.sub.2] = CN, COOMe, PhCH=CH, Cl, Me, OMe) sur l'anneau de la pyrazine a revele une forte dependance des effets electroniques sur la regio-chimie de l'addition nucleophilique. Mots-cles: pyrazines, γ-lactones, N-activation., Introduction Nitrogen heterocycles are abundant in nature and are of great significance to life because their structural subunits exist in many natural products such as vitamins, hormones, antibiotics, and alkaloids, [...]

Iodine promotes the in situ formation of iron(II) species from η4-vinylketene[Fe(CO)3] (3a–h) as a key intermediate for the synthesis of 2(5H)-furanones (4a–h) by a sequential water-insertion/carbon–oxygen coupling under mild reaction conditions. Compounds 4a–h were obtained in good to excellent yields. A possible reaction pathway was also proposed by DFT calculations. This methodology can be extended to the synthesis of (5H)-pyrrol-2-ones using anilines, with moderate yields and a few limitations. [ABSTRACT FROM AUTHOR]

A set of alkyl aluminum complexes supported by non-symmetric ferrocenyl amidine ligands were used as catalysts for the preparation of cyclic carbonates from epoxides and carbon dioxide using Bu4NI as a co-catalyst. A modified method for the synthesis of aminoferrocene allowed us to obtain this precursor in quantitative yield. Treatment of aminoferrocene with the corresponding acetimidoyl chloride afforded the desired ferrocenyl amidine ligands L1H, (E)-N-(2,6-diisopropylphenyl)-N'-(ferrocenyl)acetimidamide, and L2H, (E)-N-(2,6-dimethylphenyl)-N'-(ferrocenyl)acetimidamide. The reaction of these ligands with 1.0 or 0.5 equiv. of AlMe3 led to the synthesis of aminoferrocene based aluminum complexes ((L1)AlMe2 (1), (L2)AlMe2 (2), (L1)2AlMe (3), and (L2)2AlMe (4)) in excellent yields, which were characterized by spectroscopic and X-ray diffraction methods. In addition, we have studied their electrochemical properties and complex 1 was found to be the most active catalyst for the formation of cyclic carbonates 6a–j from their corresponding epoxides 5a–j and CO2. [ABSTRACT FROM AUTHOR]

The synthesis and spectroscopic and structural properties of copper(I) complexes with 3-hydroxy-3-(p-R-phenyl)-2-propenedithioic acids ligands are reported in the study. The dithioate-coordination fashion of these ligands is observed for the first time.

The synthesis of four amphiphilic organometallic complexes with the general formula RC = M(CO)5NH(CH2)15CH3, where R is a ferrocenyl 2(a-b) or a phenyl 4(a-b) group as a donor moiety and a Fischer carbene of chromium (0) or tungsten (0) as an acceptor group, are reported. These four push-pull systems formed Langmuir (L) monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area and compression/expansion cycles (hysteresis curves); Brewster angle microscopic images were also obtained. By using the Langmuir-Blodgett (LB) method, molecular monolayers were transferred onto glass substrates forming Z-type multilayers. LB films were characterized through ultraviolet-visible spectroscopy, atomic force microscopy and X-ray diffraction techniques. Results indicated that films obtained from 2b complex [(Ferrocenyl)(hexadecylamine)methylidene] pentacarbonyl tungsten (0) are the most stable and homogeneous; due to their properties, these materials may be incorporated into organic electronic devices. [ABSTRACT FROM AUTHOR]

The reaction of Fe2(CO)9 with α,β-unsaturated ketones analogues containing β-positioned sulfoxide group 2a–2d afforded dinuclear Fe(0) complexes 3a–3d and 5 which were characterized by IR, mass spectrometry, 1H and 13C NMR spectroscopy, the structures of 3a, 3c and 5 were established by X-ray diffraction analysis. [Copyright &y& Elsevier]

We herein report the synthesis and catalytic application of a new family of dinuclear Cu(I) complexes based on [N,P]-pyrrole ligands. The Cu(I) complexes (4a-d) were obtained in good yields and their catalytic properties were evaluated in the1,3-dipolar cycloaddition of azomethine ylides and electron-deficient alkenes. The air-stable complexes 4a-d exhibited high endo-diasteroselectivity to obtain substituted pyrrolidines, and the catalytic system showed excellent reactivity and wide substitution tolerance.

The synthesis of a series of ferrocenylvinylketenes as stable η 4 -[Fe(CO) 3 ] complexes (3a-f) was successfully accomplished through the reaction of η 2 -[Fe(CO) 4 ] complexes under mild carbonylation conditions. The reactivity of 3a-f under thermal conditions afforded the unexpected formation of a novel family of (μ 2 ,η 3 -allyl-η 5 -oxapentadienyl)diiron pentacarbonyl complexes 5a-f proposed to be formed by a sequence metathesis-haptotropic rearrangement between the starting η 4 -vinylketene iron(0) complex 3 and a η 4 -vinylcarbene iron(0) complex trapped in situ after a reversible carbonylation process favored by the thermal conditions. An electron density distribution analysis (EDD) of 5e using high-resolution X-ray diffraction data in combination with the DFT framework was performed to understand the electronic communication between the two iron fragments.

Iodine promotes the in situ formation of iron(II) species from η 4 -vinylketene[Fe(CO) 3 ] (3a-h) as a key intermediate for the synthesis of 2(5 H )-furanones (4a-h) by a sequential water-insertion/carbon-oxygen coupling under mild reaction conditions. Compounds 4a-h were obtained in good to excellent yields. A possible reaction pathway was also proposed by DFT calculations. This methodology can be extended to the synthesis of (5 H )-pyrrol-2-ones using anilines, with moderate yields and a few limitations.

A set of alkyl aluminum complexes supported by non-symmetric ferrocenyl amidine ligands were used as catalysts for the preparation of cyclic carbonates from epoxides and carbon dioxide using Bu4NI as a co-catalyst. A modified method for the synthesis of aminoferrocene allowed us to obtain this precursor in quantitative yield. Treatment of aminoferrocene with the corresponding acetimidoyl chloride afforded the desired ferrocenyl amidine ligands L1H, (E)-N-(2,6-diisopropylphenyl)-N'-(ferrocenyl)acetimidamide, and L2H, (E)-N-(2,6-dimethylphenyl)-N'-(ferrocenyl)acetimidamide. The reaction of these ligands with 1.0 or 0.5 equiv. of AlMe3 led to the synthesis of aminoferrocene based aluminum complexes ((L1)AlMe2 (1), (L2)AlMe2 (2), (L1)2AlMe (3), and (L2)2AlMe (4)) in excellent yields, which were characterized by spectroscopic and X-ray diffraction methods. In addition, we have studied their electrochemical properties and complex 1 was found to be the most active catalyst for the formation of cyclic carbonates 6a-j from their corresponding epoxides 5a-j and CO2.