- Rapid Asymmetric Synthesis of Disubstituted Allenes by Coupling of Flow-Generated Diazo Compounds and Propargylated Amines
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We report herein the asymmetric coupling of flow-generated unstabilized diazo compounds and propargylated amine derivatives, using a new pyridinebis(imidazoline) ligand, a copper catalyst and base. The reaction proceeds rapidly, generating chiral allenes in 10–20 minutes with high enantioselectivity (89–98 % de/ee), moderate yields and a wide functional group tolerance.
- Poh, Jian-Siang,Makai, Szabolcs,von Keutz, Timo,Tran, Duc N.,Battilocchio, Claudio,Pasau, Patrick,Ley, Steven V.
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supporting information
p. 1864 - 1868
(2017/02/05)
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- Calix[6]arene-picolinamide extractants for radioactive waste treatment: Effect of additional carboxy binding Sites in the pyridine 6-positions on complexation, extraction efficiency and An/Ln separation
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The effect of the presence of an additional ester or amide carboxy group in the 6-position of the pyridine nuclei of calixarene-based picolinamide ligands on the extraction and complexation properties of lanthanide(III) and actinide(III) metal ions was studied. For this purpose, six new ligands 1-6 were synthesized; their conformational properties were studied both in solution and in the solid state, and their binding properties towards lanthanide (Ln III) and actinide (AnIII) metal ions were determined under extracting conditions simulating those present in radioactive waste. In the presence of BrCosan as synergizer, a rather high efficiency in the extraction of trivalent metal ions by these ligands was observed even at [HNO3] > 2-3 M. Complexation of LnIII metal ions was also studied under homogeneous conditions (methanol solution), both in chloride and nitrate media, by using spectrophotometry and calorimetry. A comparison with the data obtained with ligands L1-L3, lacking the additional binding sites in the 6-position of the pyridine nuclei, is reported and the effects of the structure of the ligands on the stoichiometry of the complexes, coordination of the metal ions, basicity of the pyridine binding groups and efficiency and selectivity in the extractions are also discussed.
- Macerata, Elena,Sansone, Francesco,Baldini, Laura,Ugozzoli, Franco,Brisach, Frederic,Haddaoui, Jaouad,Hubscher-Bruder, Veronique,Arnaud-Neu, Francoise,Mariani, Mario,Ungaro, Rocco,Casnati, Alessandro
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experimental part
p. 2675 - 2686
(2010/08/05)
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- Novel late transition metal catalysts based on iron: Synthesis, structures and ethylene polymerization
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In this article we reported synthesis, characterization and ethylene polymerization behavior of two new late transition metal 2,6-bis(imino)pyridine catalysts based on iron(II) possessing different substituents of NO2 (catalyst b) and OMe (catalyst c) at the para position of the pyridine ring. Theoretical study exhibited more positive charge on the central metal of the catalyst b, leading to higher activity offset by lower thermal stability and life time.
- Zohuri, Gholam Hossein,Seyedi, Seyed Mohammad,Sandaroos, Reza,Damavandi, Saman,Mohammadi, Ali
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p. 160 - 166
(2011/10/03)
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- Chelate bis(imino)pyridine cobalt complexes: Synthesis, reduction, and evidence for the generation of ethene polymerization catalysts by Li+ cation activation
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Treatment of the bis(iminobenzyl)pyridine chelate Schiff-base ligand 8 (ligPh) with FeCl2 or CoCl2 yielded the corresponding (ligPh)MCl2 complexes 9 (Fe) and 10 (Co). The reaction of 10 with methyllithium or "butadiene-magnesium" resulted in reduction to give the corresponding (ligPh)Co(I)Cl product 11. Similarly, the bis(aryliminoethyl)pyridine ligand (ligMe) was reacted with CoCl2 to yield (ligMe)CoCl2 (12). Reduction to (ligMe)CoCl (13) was effected by treatment with "butadiene-magnesium". Complex 13 reacted with Li[B(C 6F5)4] in toluene followed by treatment with pyridine to yield [(ligMe)Co+-pyridine] (15). The reaction of the Co(II) complexes 10 or 12 with ca. 3 molar equiv of methyllithium gave the cobalt(I) complexes 16 and 17, respectively. Treatment of the (lig Me)CoCH3 (17) with Li[B(C6F5) 4] gave a low activity ethene polymerization catalyst. Likewise, complex 16 produced polyethylene (activity = 33 g(PE) mmol(cat)-1 h-1 bar-1 at room temperature) upon treatment with a stoichiometric amount of Li[B(C6F5)4]. A third ligand (ligOMe) was synthesized featuring methoxy groups in the ligand backbone (22). Coordination to FeCl2 and CoCl2 yielded the desired compounds 23 and 24. Reaction with MeLi gave (lig OMe)CoMe (25/26). Treatment of 25/26 with excess B(C 6F5)3 gave the η6-arene cation complex 27, where one Co-N linkage was cleaved. Activation of 25/26 with Li[B(C6F5)4] again gave a catalytically active species.
- Kleigrewe, Nina,Steffen, Winfried,Bloemker, Tobias,Kehr, Gerald,Froehlich, Roland,Wibbeling, Birgit,Erker, Gerhard,Wasilke, Julia-Christina,Wu, Guang,Bazan, Guillermo C.
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p. 13955 - 13968
(2007/10/03)
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