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A. J. L. Pombeiro - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Chemistry of the (η6-Cymene)ruthenium(II) Fragment With Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical and Catalytic Diastereoselective Nitroaldol Reaction Studies
    'American Chemical Society (ACS)', 2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N3, PF6, or CF3SO3) are prepared by treatment of [Ru(η6-p-cymene)Cl2]2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp4Bo = hydrotris(indazol-1-yl)borate, L = Tp4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = TpBn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η6-p-cymene)(Ph2Bp)Cl] (1) and [Ru(η6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever EL ligand parameter. The complexes [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

  • Coordination Chemistry of the (η6-p-Cymene)ruthenium(II) Fragment with Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical, and Catalytic Diastereoselective Nitroaldol Reaction Studies
    2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N 3, PF 6, or CF 3SO 3) are prepared by treatment of [Ru(η 6-p-cymene)Cl 2] 2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp 4Bo = hydrotris(indazol-1-yl)borate, L = Tp 4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = Tp Bn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η 6-p-cymene)(Ph 2Bp)Cl] (1) and [Ru(η 6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever E L ligand parameter. The complexes [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

Marcelo Gonçalves Montes D'oca - One of the best experts on this subject based on the ideXlab platform.

  • O uso de auxiliares quirais cicloexilicos na adição de nucleofilos a ions N-aciliminios ciclicos : a reação de aliltrimetilsilano com ions iminios e N-aciliminios em fase gasosa
    2017
    Co-Authors: Marcelo Gonçalves Montes D'oca
    Abstract:

    Resumo: A primeira parte deste trabalho trata da determinação da razão diastereoisomérica (r.d.) da a-amidoalquilação assimétrica de íons N-acilimínios quirais derivados da pirrolidina e piperidina com aliltrimetilsilano e 2-terc-butildimetilsililoxifurano, utilizando auxiliares quirais cicloexílicos. Inicialmente, foi investigada a seletividade facial dos intermediários N-acilimínios quirais de 5-, e 6- membros frente a adição nucleofílica de aliltrimetilsilano. A reação ocorreu com bons rendimentos e baixa seletividade (r.d. = 1:1-2:1) quando (1R,2S)-trans-fenilcicloexanol foi usado como auxiliar quiral. Entretanto foi possível aumentar a seletividade (r.d. = 3:1-6:1) da reação fazendo o uso do (-)-8-fenilmentol como auxiliar quiral. Neste último caso caso a formação dos produtos majoritários foi atribuída a um ataque nucleofílico do aliltrimetilsilano a face Si do íon N-acilimínio levando a configuração absoluta R para o novo centro assimétrico a-nitrogênio. Em ambos os casos, os auxiliares quirais foram recuperados em bons rendimentos. Após foi investigada a reação de Mannich viníloga utilizando o nucleófilo proquiral 2-terc-butildimetilsililoxifurano. Em todos os casos, dos quatro possíveis diastereoisômeros, somente dois foram formados. Tanto com o uso do ( 1R,2S )-trans-fenilcicloexanol como para o (-)-8-fenilmentol como auxiliares quirais o ataque nucleofílico ocorreu exclusivamente a face Si do íon N-acilimínio e formação de misturas diastereoisoméricas (r.d. = 2:1-7:1) foi atribuída à moderada seletividade facial do nucleófilo 2-terc-butildimetilsililoxifurano. Os adutos majoritários apresentaram configuração absoluta R para os dois centros estereogênicos formados (C5 e C2´), mostrando a preferência pelo produto de configuração relativa treo (anti), consistente com os exemplos mostrados na literatura. Esta nova metodologia permitiu a construção dos alcalóides (S)-2-propil pirrolidina e enantiomericamente enriquecida (S)-coniina e de intermediários indolizidínicos e quinolizídinicos (5R,6R)-5-hidróxi-1-azabiciclo[4.3.0]nonano-2-ona e (5R,6R)-5-hidróxi-1-azabiciclo[4.4.0]decano-2-ona, que são de interesse por estarem presentes em sistemas do tipo pumiliotoxina e homopumiliotoxina, respectivamente. Na segunda parte, investigou-se a reação de a-amidoalquilação de íons imínios e N-acilimínios de 5- e 6- membros em fase gasosa, frente à adição dos nucleófilos viniltrimetilsilano e aliltrimetilsilano. Este estudo foi realizado em um aparelho de massa pentaquadrupolar onde íons gerados a partir da ionização por impacto de elétrons de aminas, lactamas, amidas e carbamatos, reagiram isoladamente com viniltrimetilsilano ou aliltrimetilsilano. A reação ocorreu apenas para a adição de aliltrimetilsilano a íons N-acilimínios derivados de lactamas e carbamatos e levou a formação de intermediários catiônicos b ao átomo de silício. A ordem de reatividade observada para os íons N-acilimínios derivados foi de carbamatos >> lactamas > amidas, em todos os casos os íons N-acilimínios de 5-membros foram mais reativos que os de 6-membros frente à reação de a-amidoalquilação. Este estudo mostrou a formação de intermediários catiônicos b ao átomo de silício (efeito b-silício) em fase gasosa.Abstract: The first part of this work comprises the determination of the diastereoIsomeric ratio (d.r.) in the asymmetric a-amidoalkylation of chiral 5- and 6-membered N-acyliminium ions bearing cyclohexyl-based chiral auxiliaries with allyltrimethylsilane and 2-tert-butyldimethylsilyloxyfuran. The addition of allyltrimethylsilane to chiral 5- and 6-membered N-acyliminium ions derived from (1R,2S)-trans-phenylcyclohexanol took place with good yields and low diastereoselection (d.r. = 1:1-2:1). However, the diastereoselection improved (d.r. = 3:1-6:1) when (-)-8-phenylmenthol was employed as the chiral auxiliary. The formation of the major diastereoIsomer was rationalized through the addition of the nucleophile to the Si face of the chiral N-acyliminium ion. In both cases, efficient recovery of the chiral auxiliaries was achieved. The addition of 2-tert-butyldimethylsilyloxyfuran to chiral 5- and 6-membered N-acyliminium ions afforded only two out of the four possible diastereIsomers with the addition of the prochiral nucleophile also to the Si face of the chiral N-acyliminium ions and the mixture of butenolides formed (d.r. = 2:1-7:1) resulted from low to moderate facial selection of the nucleophile. In all cases, the major diastereoIsomer displayed R configuration at both newly created stereocenters (Threo Isomer) in accordance with related examples in the literature. This methodology allowed the preparation of optically pure (S)-2-propyl pyrrolidine and enantiomerically enriched (S)-coniine as well as (5R,6R)-5-hydroxy-1-azabicyclo[4.3.0]nonane-2-one and (5R,6R)-5-hydroxy-1-azabicyclo[4.4.0]nonane-2-one which are of synthetic interest for the preparation of pumiliotoxin and homopumiliotoxin alkaloids, respectively. In the second part of this work, the a-amidoalkylation of the 5- and 6-membered iminium and N-acyliminium ions with vinyl- and allyltrimethylsilane in the gas phase was investigated. This study was carried out in a pentaquadrupolar mass spectrometer and the iminium and N-acyliminium ions were generated by ionization of the corresponding amines, lactams, amides and carbamates, followed by addition of vinyl- or allyltrimethylsilane. Gas phase reaction was observed only when allyltrimethylsilane was added to N-acyliminium ions derived from amides and carbamates and allowed the observation of cationic species intermediates b to the silicon atom. The N-acyliminium ions derived from carbamates were more reactive than the ones derived from amides and in all cases 5-membered N-acyliminium ions proved to be more reactive than corresponding 6-membered analogues. Theses results clearly demonstrated the formation of a cationic intermediates b to the silicon atom (silicon b-effect) in the gas phase

  • O uso de auxiliares quirais cicloexilicos na adição de nucleofilos a ions N-aciliminios ciclicos : a reação de aliltrimetilsilano com ions iminios e N-aciliminios em fase gasosa
    Universidade Estadual de Campinas . Instituto de Quimica, 2000
    Co-Authors: Marcelo Gonçalves Montes D'oca
    Abstract:

    A primeira parte deste trabalho trata da determinação da razão diastereoisomérica (r.d.) da a-amidoalquilação assimétrica de íons N-acilimínios quirais derivados da pirrolidina e piperidina com aliltrimetilsilano e 2-terc-butildimetilsililoxifurano, utilizando auxiliares quirais cicloexílicos. Inicialmente, foi investigada a seletividade facial dos intermediários N-acilimínios quirais de 5-, e 6- membros frente a adição nucleofílica de aliltrimetilsilano. A reação ocorreu com bons rendimentos e baixa seletividade (r.d. = 1:1-2:1) quando (1R,2S)-trans-fenilcicloexanol foi usado como auxiliar quiral. Entretanto foi possível aumentar a seletividade (r.d. = 3:1-6:1) da reação fazendo o uso do (-)-8-fenilmentol como auxiliar quiral. Neste último caso caso a formação dos produtos majoritários foi atribuída a um ataque nucleofílico do aliltrimetilsilano a face Si do íon N-acilimínio levando a configuração absoluta R para o novo centro assimétrico a-nitrogênio. Em ambos os casos, os auxiliares quirais foram recuperados em bons rendimentos. Após foi investigada a reação de Mannich viníloga utilizando o nucleófilo proquiral 2-terc-butildimetilsililoxifurano. Em todos os casos, dos quatro possíveis diastereoisômeros, somente dois foram formados. Tanto com o uso do ( 1R,2S )-trans-fenilcicloexanol como para o (-)-8-fenilmentol como auxiliares quirais o ataque nucleofílico ocorreu exclusivamente a face Si do íon N-acilimínio e formação de misturas diastereoisoméricas (r.d. = 2:1-7:1) foi atribuída à moderada seletividade facial do nucleófilo 2-terc-butildimetilsililoxifurano. Os adutos majoritários apresentaram configuração absoluta R para os dois centros estereogênicos formados (C5 e C2´), mostrando a preferência pelo produto de configuração relativa treo (anti), consistente com os exemplos mostrados na literatura. Esta nova metodologia permitiu a construção dos alcalóides (S)-2-propil pirrolidina e enantiomericamente enriquecida (S)-coniina e de intermediários indolizidínicos e quinolizídinicos (5R,6R)-5-hidróxi-1-azabiciclo[4.3.0]nonano-2-ona e (5R,6R)-5-hidróxi-1-azabiciclo[4.4.0]decano-2-ona, que são de interesse por estarem presentes em sistemas do tipo pumiliotoxina e homopumiliotoxina, respectivamente. Na segunda parte, investigou-se a reação de a-amidoalquilação de íons imínios e N-acilimínios de 5- e 6- membros em fase gasosa, frente à adição dos nucleófilos viniltrimetilsilano e aliltrimetilsilano. Este estudo foi realizado em um aparelho de massa pentaquadrupolar onde íons gerados a partir da ionização por impacto de elétrons de aminas, lactamas, amidas e carbamatos, reagiram isoladamente com viniltrimetilsilano ou aliltrimetilsilano. A reação ocorreu apenas para a adição de aliltrimetilsilano a íons N-acilimínios derivados de lactamas e carbamatos e levou a formação de intermediários catiônicos b ao átomo de silício. A ordem de reatividade observada para os íons N-acilimínios derivados foi de carbamatos >> lactamas > amidas, em todos os casos os íons N-acilimínios de 5-membros foram mais reativos que os de 6-membros frente à reação de a-amidoalquilação. Este estudo mostrou a formação de intermediários catiônicos b ao átomo de silício (efeito b-silício) em fase gasosa.The first part of this work comprises the determination of the diastereoIsomeric ratio (d.r.) in the asymmetric a-amidoalkylation of chiral 5- and 6-membered N-acyliminium ions bearing cyclohexyl-based chiral auxiliaries with allyltrimethylsilane and 2-tert-butyldimethylsilyloxyfuran. The addition of allyltrimethylsilane to chiral 5- and 6-membered N-acyliminium ions derived from (1R,2S)-trans-phenylcyclohexanol took place with good yields and low diastereoselection (d.r. = 1:1-2:1). However, the diastereoselection improved (d.r. = 3:1-6:1) when (-)-8-phenylmenthol was employed as the chiral auxiliary. The formation of the major diastereoIsomer was rationalized through the addition of the nucleophile to the Si face of the chiral N-acyliminium ion. In both cases, efficient recovery of the chiral auxiliaries was achieved. The addition of 2-tert-butyldimethylsilyloxyfuran to chiral 5- and 6-membered N-acyliminium ions afforded only two out of the four possible diastereIsomers with the addition of the prochiral nucleophile also to the Si face of the chiral N-acyliminium ions and the mixture of butenolides formed (d.r. = 2:1-7:1) resulted from low to moderate facial selection of the nucleophile. In all cases, the major diastereoIsomer displayed R configuration at both newly created stereocenters (Threo Isomer) in accordance with related examples in the literature. This methodology allowed the preparation of optically pure (S)-2-propyl pyrrolidine and enantiomerically enriched (S)-coniine as well as (5R,6R)-5-hydroxy-1-azabicyclo[4.3.0]nonane-2-one and (5R,6R)-5-hydroxy-1-azabicyclo[4.4.0]nonane-2-one which are of synthetic interest for the preparation of pumiliotoxin and homopumiliotoxin alkaloids, respectively. In the second part of this work, the a-amidoalkylation of the 5- and 6-membered iminium and N-acyliminium ions with vinyl- and allyltrimethylsilane in the gas phase was investigated. This study was carried out in a pentaquadrupolar mass spectrometer and the iminium and N-acyliminium ions were generated by ionization of the corresponding amines, lactams, amides and carbamates, followed by addition of vinyl- or allyltrimethylsilane. Gas phase reaction was observed only when allyltrimethylsilane was added to N-acyliminium ions derived from amides and carbamates and allowed the observation of cationic species intermediates b to the silicon atom. The N-acyliminium ions derived from carbamates were more reactive than the ones derived from amides and in all cases 5-membered N-acyliminium ions proved to be more reactive than corresponding 6-membered analogues. Theses results clearly demonstrated the formation of a cationic intermediates b to the silicon atom (silicon b-effect) in the gas phase

C. Pettinari - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Chemistry of the (η6-Cymene)ruthenium(II) Fragment With Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical and Catalytic Diastereoselective Nitroaldol Reaction Studies
    'American Chemical Society (ACS)', 2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N3, PF6, or CF3SO3) are prepared by treatment of [Ru(η6-p-cymene)Cl2]2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp4Bo = hydrotris(indazol-1-yl)borate, L = Tp4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = TpBn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η6-p-cymene)(Ph2Bp)Cl] (1) and [Ru(η6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever EL ligand parameter. The complexes [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

  • Coordination Chemistry of the (η6-p-Cymene)ruthenium(II) Fragment with Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical, and Catalytic Diastereoselective Nitroaldol Reaction Studies
    2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N 3, PF 6, or CF 3SO 3) are prepared by treatment of [Ru(η 6-p-cymene)Cl 2] 2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp 4Bo = hydrotris(indazol-1-yl)borate, L = Tp 4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = Tp Bn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η 6-p-cymene)(Ph 2Bp)Cl] (1) and [Ru(η 6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever E L ligand parameter. The complexes [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

F. Marchetti - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Chemistry of the (η6-Cymene)ruthenium(II) Fragment With Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical and Catalytic Diastereoselective Nitroaldol Reaction Studies
    'American Chemical Society (ACS)', 2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N3, PF6, or CF3SO3) are prepared by treatment of [Ru(η6-p-cymene)Cl2]2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp4Bo = hydrotris(indazol-1-yl)borate, L = Tp4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = TpBn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η6-p-cymene)(Ph2Bp)Cl] (1) and [Ru(η6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever EL ligand parameter. The complexes [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

  • Coordination Chemistry of the (η6-p-Cymene)ruthenium(II) Fragment with Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical, and Catalytic Diastereoselective Nitroaldol Reaction Studies
    2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N 3, PF 6, or CF 3SO 3) are prepared by treatment of [Ru(η 6-p-cymene)Cl 2] 2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp 4Bo = hydrotris(indazol-1-yl)borate, L = Tp 4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = Tp Bn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η 6-p-cymene)(Ph 2Bp)Cl] (1) and [Ru(η 6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever E L ligand parameter. The complexes [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

A. Cerquetella - One of the best experts on this subject based on the ideXlab platform.

  • Coordination Chemistry of the (η6-Cymene)ruthenium(II) Fragment With Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical and Catalytic Diastereoselective Nitroaldol Reaction Studies
    'American Chemical Society (ACS)', 2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N3, PF6, or CF3SO3) are prepared by treatment of [Ru(η6-p-cymene)Cl2]2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp4Bo = hydrotris(indazol-1-yl)borate, L = Tp4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = TpBn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η6-p-cymene)(Ph2Bp)Cl] (1) and [Ru(η6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever EL ligand parameter. The complexes [Ru(η6-p-cymene)(κ2-L)X] and [Ru(η6-p-cymene)(κ3-L)]X•nH2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer

  • Coordination Chemistry of the (η6-p-Cymene)ruthenium(II) Fragment with Bis-, Tris-, and Tetrakis(pyrazol-1-yl)borate Ligands: Synthesis, Structural, Electrochemical, and Catalytic Diastereoselective Nitroaldol Reaction Studies
    2011
    Co-Authors: C. Pettinari, F. Marchetti, A. Cerquetella, R. Pettinari, M. Monari, T. Mac C. O. Leod, L. M. D. R. S. Martins, A. J. L. Pombeiro
    Abstract:

    Novel [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O complexes (L = bis-, tris-, or tetrakis-pyrazolylborate; X = Cl, N 3, PF 6, or CF 3SO 3) are prepared by treatment of [Ru(η 6-p-cymene)Cl 2] 2 with poly(pyrazolyl)borate derivatives [M(L)] (L in general; in detail L = Ph 2Bp = diphenylbis(pyrazol-1-yl)borate; L = Tp = hydrotris(pyrazol-1- yl)borate; L = pzTp = tetrakis(pyrazol-1-yl)borate; L = Tp 4Bo = hydrotris(indazol-1-yl)borate, L = Tp 4Bo,5Me = hydrotris(5- methylindazol-1-yl)borate; L = Tp Bn,4Ph = hydrotris(3-benzyl-4- phenylpyrazol-1-yl)borate; M = Na, K, or Tl) and characterized by analytical and spectral data (IR, ESIMS, 1H and 13C NMR). The structures of [Ru(η 6-p-cymene)(Ph 2Bp)Cl] (1) and [Ru(η 6-p-cymene)(Tp)Cl] (3) have been established by single-crystal X-ray diffraction analysis. Electrochemical studies allowed comparing the electron-donor characters of Tp and related ligands and estimating the corresponding values of the Lever E L ligand parameter. The complexes [Ru(η 6-p-cymene)(κ 2-L)X] and [Ru(η 6-p-cymene)(κ 3-L)]X•nH 2O act as catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehyde and nitroethane to the corresponding β-nitroalkanol (up to 82% yield, at room temperature) with diastereoselectivity toward the formation of the Threo Isomer