- A hydrogen borrowing annulation strategy for the stereocontrolled synthesis of saturated aza-heterocycles
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An iridium catalyzed method for the synthesis of saturated aza-heterocycles from amines and diols is reported. A wide range of substituted heterocycles can be obtained using this approach including products bearing substituents at the C2, C3 and C4 positions. Employing water as the solvent, enantiopure diols could undergo annulation with minimal racemization, enabling the synthesis of valuable enantioenriched C3 and C4-substituted saturated aza-heterocycles.
- Armstrong, Roly J.,Chamberlain, Anna E. R.,Donohoe, Timothy J.,Paterson, Kieran J.,Twin, Heather C.
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p. 3563 - 3566
(2020/04/03)
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- Hydrazone complexes of ruthenium(II): Synthesis, crystal structures and catalytic applications in N-alkylation reactions
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A series of new Ru(II) complexes of 8-hydroxy quinoline-2-carboxyaldehyde hydrazone of the general formula [RuH(CO)(EPh3)2L] (1–6) (E = P or As, L = N’-((8-hydroxyquinolin-2-yl)methylene)thiophene-2-carbohydrazide (HQ-THy), N’-((8-hydroxyquinolin-2-yl)methylene)isonicotinohydrazide (HQ-IHy), N’-((8-hydroxyquinolin-2-yl)methylene) benzohydrazide (HQ-BHy)) have been synthesized. They have been characterized by elemental analysis, IR, NMR (1H, 13C & 31P) and ESI-MS spectral methods. Further, structures of two of the complexes have been determined by single crystal X-ray diffraction technique which revealed a pseudo octahedral geometry with the coordination of the quinoline nitrogen and quinoline oxygen atoms of the ligand. All the new complexes have been employed as efficient catalysts in N-alkylation reactions for the synthesis of tertiary amines by the coupling of secondary amines with aromatic primary alcohols at low catalyst loading with maximum yields. In addition, the effects of substituents on the ligands, different solvents as well as bases and amounts of catalyst loading on the catalytic activity of the complexes have been thoroughly investigated. Complex 1 was found to be efficient catalyst towards N-alkylation of alcohols with the amine. Further, a variety of secondary amines and aromatic (hetero) primary alcohols with various functional groups have also been successfully used in the N-alkylation reactions and it has been found that only one equivalent of the alcohol was consumed in the process.
- Murugan, Kaliyappan,Natarajan, Karuppannan,Nirmala, Muthukumaran,Vijayapritha, Subbarayan,Viswanathamurthi, Periasamy
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- Half-sandwich ruthenium-carbene catalysts: Synthesis, characterization, and catalytic application in the N-alkylation of amines with alcohols
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In this study, the synthesis and characterization of new half-sandwich ruthenium complexes containing oxygen functionalised N-aryl and N-alkyl benzimidazol-2-ylidene ligands have been reported. All ruthenium complexes were tested as catalysts for a wide range of substrates in the N-alkylation of secondary cyclic amines such as pyrrolidine and piperidine, and 4-methylaniline which was a primary aromatic amine with alcohols by hydrogen-borrowing process. The catalytic reactions were performed with 1 mol% catalyst loading at 120 °C, 16 h under solvent-free conditions. All ruthenium complexes showed excellent catalytic activity, and N-alkylated products were obtained selectively.
- Kalo?lu, Murat
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- Ruthenium(II) and iridium(III) complexes featuring NHC-sulfonate chelate
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Three new complexes bearing a chelating (κ2C,O) NHC-SO3 ligand have been prepared. An original method for the synthesis of the imidazolium-sulfonate NHC precursor is described. The 5-membered ruthena- and irida-cycle containing complexes were fully characterized and evaluated in a series of catalytic transformations involving hydrogen auto-transfer processes.
- Rajaraman,Sahoo,Hild,Fischmeister,Achard,Bruneau
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supporting information
p. 17467 - 17472
(2015/10/19)
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- Sp3 C-H bond activation with ruthenium(II) catalysts and C(3)-alkylation of cyclic amines
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A selective C(3)-alkylation via activation/functionalization of sp 3 C-H bond of saturated cyclic amines was promoted by (arene)ruthenium(II) complexes featuring a bidentate phosphino-sulfonate ligand upon reaction with aldehydes. This highly regioselective sustainable transformation takes place via initial dehydrogenation of cyclic amines and hydrogen autotransfer processes.
- Sundararaju, Basker,Achard, Mathieu,Sharma, Gangavaram V. M.,Bruneau, Christian
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p. 10340 - 10343
(2011/08/05)
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- Ruthenium-catalyzed cascade N- and C(3)-dialkylation of cyclic amines with alcohols involving hydrogen autotransfer processes
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An unprecented N- and C(3)-dialkylation of unactivated amines by a cascade reaction via borrowing hydrogen methodology using new (arene)ruthenium(II) complexes featuring phosphinosulfonate ligands is described. This reaction is highly regioselective and produces water as the only side product. Copyright
- Sundararaju, Basker,Tang, Zhou,Achard, Mathieu,Sharma, Gangavaram V. M.,Toupet, Loic,Bruneau, Christian
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supporting information; experimental part
p. 3141 - 3146
(2011/02/28)
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