- A Ruthenium Catalyst with Unprecedented Effectiveness for the Coupling Cyclization of - Amino Alcohols and Secondary Alcohols
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The ruthenium complex (8-(2-diphenylphosphinoethyl)aminotrihydroquinolinyl)(carbonyl)(hydrido)ruthenium chloride exhibited extremely high efficiency toward the coupling cyclization of -amino alcohols with secondary alcohols. The corresponding products, pyridine or quinoline derivatives, are obtained in good to high isolated yields. On comparison with literature catalysts whose noble-metal loading with respect to -amino alcohols reached 0.5-1.0 mol % for Ru and a record lowest of 0.04 mol % for Ir, the current catalyst achieves the same efficiency with a loading of 0.025 mol % for Ru. The mechanism of acceptorless dehydrogenative condensation (ADC) was proposed on the basis of DFT calculations; in addition, the reactive intermediates were determined by GC-MS, NMR, and single-crystal X-ray diffraction. The catalytic process is potentially suitable for industrial applications.
- Pan, Bing,Liu, Bo,Yue, Erlin,Liu, Qingbin,Yang, Xinzheng,Wang, Zheng,Sun, Wen-Hua
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p. 1247 - 1253
(2016/02/18)
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- Synthesis of pyridines and pyrazines using an intramolecular hydroamination-based reaction sequence
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A management issue! Various pyridines and pyrazines can be efficiently accessed from simple acyclic precursors using an intramolecular hydroamination/isomerization/aromatization sequence (see scheme). ρ-Toluenesulfonic acid (2 mol%) is used to catalyze this novel alkyne annulation, in which the oxime group allows for a subsequent redoxneutral aromatization step to occur.
- Rizk, Toni,Bilodeau, Eric J.-F.,Beauchemin, Andre M.
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supporting information; experimental part
p. 8325 - 8327
(2010/01/16)
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- 1,2,3-Triazines,III. - Synthesis of N-Aminopyrazoles and their Oxidation to 1,2,3-Triazines. Molecular Structure of 1,2,3-Triazine
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Oxidation of the N-aminopyrazoles 4a-i affords the 1,2,3-triazines 5a-i.Spectra and reactions - such as oxidation, reduction, and cycloaddition reactions - of some 1,2,3-triazines 5 are described.The X-ray analysis of 5a is presented.
- Neunhoeffer, Hans,Clausen, Monika,Voetter, Hans-Dieter,Ohl, Harald,Krueger, Carl,Angermund, K.
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p. 1732 - 1751
(2007/10/02)
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- Reactions de cyclisation de pentynyl-2 pyrimidones-4
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Acetylenic amidines HCC-(CH2)n-C(=NH)NH2 give, by condensation with β-ketoesters, pyrimidones substituted on carbon 2 by an acetylenic chain.Two types of evolution are observed when compounds are heated without any catalyst.The minor route is a cyclization by attack on a triple bond by the amidic nitrogen atom.The main reaction is a cycloaddition involving the non activated triple bond and an azadienic system, leading to non isolated tricyclic intermediates which retrocyclize to stable bicyclic compounds.
- Rougeot, Etienne,Moskowitz, Henri,Miocque, Marcel
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p. 1407 - 1409
(2007/10/02)
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