- Cu-Catalyzed Chemoselective Reduction of N-Heteroaromatics with NH3·BH3 in Aqueous Solution
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An efficient catalytic system was successfully developed on reduction of N-heteroaromatics with H3N?BH3 as hydrogen source in CuSO4 solution, featuring excellent chemoselectivity as well as very broad functional group tolerance. Various challenging substrates, such as OH-, NH2-, Cl-, Br-, etc., contained quinolines, quinoxalines, 1,5-naphthyridines and quinazolines were all reduced smoothly. Mechanistic studies suggested that [Cu-H] intermediate might be generated from NH3?BH3, which was believed to form with H3N?BH3 in CuSO4 solution.
- Gao, Chao,Xuan, Qingqing,Song, Qiuling
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supporting information
p. 2504 - 2508
(2021/07/31)
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- Boron-Catalyzed Hydrogenative Reduction of Substituted Quinolines to Tetrahydroquinolines with Hydrosilanes
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A metal-free procedure for the hydrogenative reduction of substituted N-heteroaromatics has been developed by using hydrosilanes as reducing agents. The optimized conditions were successfully applied to the reactions of quinolines, quinoxalines, and quinoline N -oxides. They were also effective for the reduction of quinolines bearing amino or hydroxy groups, where H 2 was evolved through dehydrogenative silylation of the amine or hydroxy moieties. Preliminary mechanistic studies revealed that the initial step in the catalytic cycle involves 1,4-addition of the hydrosilane to the quinoline to give a 1,4-dihydroquinoline; this is followed by (transfer) hydrogenation to deliver the tetrahydroquinoline as the final product.
- Gandhamsetty, Narasimhulu,Park, Sehoon,Chang, Sukbok
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supporting information
p. 2396 - 2400
(2017/11/04)
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- 2,9-DIAMINO- AND 2-AMINO-8-CARBAMOYL-4-HYDROXY-ALKANOIC ACID AMIDE DERIVATIVES
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Compounds of the formula I STR1 in which R 1 is arylamino, N-aryl-N-(lower alkoxy-lower alkyl)-amino, N-aryl-N-aryl-lower alkyl-amino or heterocyclyl bonded via a ring carbon atom, X is a carbonyl or methylene group, R 2 and R 3 independently of one another are hydrogen or lower alkyl or, together with the carbon atom with which they are bonded, are a cycloalkylidene radical, R 4 is hydrogen, lower alkyl, lower alkanoyl or lower alkoxycarbonyl, R 5 is hydroxyl, lower alkanoyloxy or lower alkoxycarbonyloxy, R 6 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, cycloalkyl, cycloalkyl-lower alkyl, aryl-lower alkyl or heteroaryl-lower alkyl having 5 to 7 ring atoms in the heteroaryl ring and R 7 is hydrogen or lower alkyl, or R 6 and R. sub.7, together with the carbon atom with which they are bonded, are a cydoalkylidene radical and R 8 denotes an aliphatic, cycloaliphatic-aliphatic or heteroarylaliphatic radical, and their salts can be used as active ingredients for medicaments for treatment of high blood pressure.
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- 2,3-Dihydro and Carbocyclic Analogues of Tryptamines: Interaction with Serotonin Receptors
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Several dihydro and carbocyclic analogues of tryptamine were evaluated in order to determine the role of the heterocyclic portion of the indole nucleus on the interaction of indolealkylamines with the serotonin receptors of the rat fundus.Reduction of the C2-C3 double bond or replacement of the indole nitrogen with sp3-hybridized carbon atom results in a 50percent decrease in receptor affinity.Complete removal of the five-membered ring of N,N-dimethyltryptamine reduces affinity by an order of magnitude.It appears that an intact indole nucleus, though not entirely necessary, results in an optimal receptor interaction for the indolealkylamines examined.
- Glennon, Richard A.,Jacyno, John M.,Salley, John J.
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