3295-64-5Relevant articles and documents
Homogeneous Catalytic Hydrogenation. 2. Selective Reduction of Polynuclear Heteroaromatic Compounds Catalyzed by Chlorotris(triphenylphosphine)rhodium(I)
Fish, Richard H.,Tan, John L.,Thormodsen, Arne D.
, p. 4500 - 4505 (1984)
The selective reduction of polynuclear heteroaromatic nitrogen compounds such as quinoline, 1, 5,6-benzoquinoline, 2, 7,8-benzoquinoline, 3, acridine, 4, phenanthridine, and in one case, a sulfur heterocyclic compound, benzothiophene, 6, with chlorotris(triphenylphosphine)rhodium(I), (Ph3P)3RhCl, provided under rather mild hydrogenation conditions the corresponding saturated nitrogen and sulfur heterocyclic analogues of the above-mentioned compounds in reasonable conversion rates and total percent yields.In addition, compounds that inhibit the initial rate of hydrogenation of 1 in the conversion to 1,2,3,4-tetrahydroquinoline, 10, include pyridine, 7, 3-methylpyridine, 8, and 10 itself.These results are indicative of electronic effects in these competitive hydrogenation reactions, while 2-methylpyridine, 9, slightly reduces the rate of hydrogenation of 1, implicating a steric effect at the metal center.It was also observed that substrate 6, indole, 11, pyrrole, 12, carbazole, 13, thiophene, 14, dibenzothiophene, 15, and p-cresol, 16, enhanced the initial rate of hydrogenation of 1 to 10 by an average factor of >1.5.The substitution of deuterium gas for hydrogen gas in the reduction of 1 provided information on the reversibility of the hydrogenation step, stereoselectivity in the reduction of the 3,4-double bond, and the implication of cyclometalation reactions which caused the exchange of H for D at the 8-position and possibly the 2-position.Similar deuteration data with compound 5 strengthened the concept of dehydrogenation in the hydrogenation step and in fact provided independent evidence for the facile dehydrogenation of 1,9,9,10-tetradeuterio-9,10-dihydrophenanthridine, 19, catalyzed by (Ph3P)3RhCl. 1H NMR and IR experiments also verify some of the postulated mechanistic aspects of these selective hydrogenation reactions.
Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
, p. 8567 - 8587 (2021/06/30)
Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
[(PPh3)2NiCl2]-Catalyzed C-N bond formation reaction via borrowing hydrogen strategy: Access to diverse secondary amines and quinolines
Donthireddy,Pandey, Vipin K.,Rit, Arnab
, p. 6994 - 7001 (2021/06/09)
Commercially available [(PPh3)2NiCl2] was found to be an efficient catalyst for the mono-N-alkylation of (hetero)- A romatic amines, employing alcohols to deliver diverse secondary amines, including the drug intermediates chloropyramine (5b) and mepyramine (5c), in excellent yields (up to 97%) via the borrowing hydrogen strategy. This method shows a superior activity (TON up to 10000) with a broad substrate scope at a low catalyst loading of 1 mol % and a short reaction time. Further, this strategy is also successful in accessing various quinoline derivatives following the acceptorless dehydrogenation pathway.
Mild and efficient copper-catalyzed oxidative cyclization of oximes with 2-aminobenzyl alcohols at room temperature: synthesis of polysubstituted quinolines
Liu, Yan-Yun,Wei, Yang,Huang, Zhi-Hui,Liu, Yilin
supporting information, p. 659 - 666 (2021/02/06)
A simple and efficient ligand-free Cu-catalyzed protocol for the synthesis of polysubstituted quinolinesviaoxidative cyclization of oxime acetates with 2-aminobenzyl alcohols at room temperature has been developed. The presented approach provides a new synthetic pathway leading to polysubstituted quinolines with good functional group tolerance under mild conditions. Moreover, this transformation can be applied for the preparation of quinolines on a gram scale. Oxime acetates serve as the internal oxidants in the reactions, thus making this method very attractive.
