جهت دسترسی به کاربرگه ی زیر، از این لینک استفاده کنید. http://dl.pgu.ac.ir/handle/10722/168581
Title: Highly efficient and diastereoselective gold(I)-catalyzed synthesis of tertiary amines from secondary amines and alkynes: Substrate scope and mechanistic insights
Keywords: Gold - Chemistry;Stereoisomerism;Molecular Structure;Hydrogenation;Catalysis;Amines - Chemical Synthesis - Chemistry;Alkynes - Chemistry
Publisher: Wiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry;Germany
Description: An efficient method for the synthesis of tertiary amines through a gold(I)-catalyzed tandem reaction of alkynes with secondary amines has been developed. In the presence of ethyl Hantzsch ester and [{(tBu) 2(o-biphenyl)P}AuCl]/AgBF 4 (2 mol %), a variety of secondary amines bearing electron-deficient and electron-rich substituents and a wide range of alkynes, including terminal and internal aryl alkynes, aliphatic alkynes, and electron-deficient alkynes, underwent a tandem reaction to afford the corresponding tertiary amines in up to 99 % yield. For indolines bearing a preexisting chiral center, their reactions with alkynes in the presence of ethyl Hantzsch ester catalyzed by [{(tBu) 2(o-biphenyl)P}AuCl]/AgBF 4 (2 mol %) afforded tertiary amines in excellent yields and with good to excellent diastereoselectivity. All of these organic transformations can be conducted as a one-pot reaction from simple and readily available starting materials without the need of isolation of air/moisture-sensitive enamine intermediates, and under mild reaction conditions (mostly room temperature and mild reducing agents). Mechanistic studies by NMR spectroscopy, ESI-MS, isotope labeling studies, and DFT calculations on this gold(I)-catalyzed tandem reaction reveal that the first step involving a monomeric cationic gold(I)-alkyne intermediate is more likely than a gold(I)-amine intermediate, a three-coordinate gold(I) intermediate, or a dinuclear gold(I)-alkyne intermediate. These studies also support the proposed reaction pathway, which involves a gold(I)-coordinated enamine complex as a key intermediate for the subsequent transfer hydrogenation with a hydride source, and reveal the intrinsic stereospecific nature of these transformations observed in the experiments. Producing tertiary amines: The Au I-catalyzed tandem reaction of alkynes with secondary amines provides simple and efficient access to highly substituted tertiary amines with excellent yields and good to excellent diastereoselectivity. Mechanistic studies confirm that a possible reaction pathway involves intermolecular hydroamination via a monomeric cationic gold(I)-alkyne intermediate and subsequent transfer hydrogenation via a gold(I)-coordinated enamine intermediate. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.;link_to_subscribed_fulltext
Other Identifiers: Chemistry - A European Journal, 2011, v. 17 n. 46, p. 12932-12945
10.1002/chem.201101982
12945
205170
WOS:000297737900019
0947-6539
46
22012740
eid_2-s2.0-80555135858
12932
http://hdl.handle.net/10722/168581
17
Type Of Material: Article
Appears in Collections:Department of Chemistry

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