Modern Chemistry
Volume 8, Issue 2, June 2020, Pages: 18-22
Received: Apr. 20, 2020; Accepted: May 5, 2020; Published: Jun. 28, 2020

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Authors

Abdol Reza Hajipour, Department of Chemistry, Isfahan University of Technology, Isfahan, Iran; Department of Neuroscience, University of Wisconsin, Madison, USA

Zahra Khorsandi, Department of Chemistry, Isfahan University of Technology, Isfahan, Iran

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Abstract

Extensive studies of asymmetric intermolecular Heck reaction are described and provide a deeper insight into histidine-catalyzed. In particular, aspects of enantio- as well as diastereoselectivity of these reactions are discussed. As the first report, we synthesized five histidine-based organocatalyts including histidine as a well-defined and biodegradable natural structure alone and in combination with 2,4,6-trichloro-1,3,5-triazine, benzene-1,3-diamine, dimethyl malonate and dimeric structure applied in the asymmetric intermolecular Heck reaction of aryl halides; their efficiency was compared to each other’s. These phosphine-free palladium catalysts were found as efficient catalytic system which provided the superior efficiency with excellent yields, regioselectivity and enantioselectivity. In these among, histidine with 2,4,6-trichloro-1,3,5-triazine which generate the star like molecule palladium catalyst gave the best activity in asymmetric intermolecular Heck reaction with excellent yields and good regio- and enantioselectivity under mild reaction conditions. The asymmetric intermolecular Heck reaction has been limited to aryl and vinyl triflates or aryl iodide in the rare reports of available Pd catalysts. Herein, we extend the reaction to aryl bromides. In addition, the scope of reaction was examined in two different techniques: conventional heating and microwave irradiation and compared. For the first time, microwave irradiation sintering is successfully used for this reaction. Comparison of catalytic activities of our catalyst (Pd/His) with literature examples confirmed our success.