N-Heterocyclic Carbene-Mediated Microfluidic Oxidative Electrosynthesis of Amides from Aldehydes

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• 作者：Robert A. Green ; Derek Pletcher ; Stuart G. Leach ; Richard C. D. Brown
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：March 4, 2016
• 年：2016
• 卷：18
• 期：5
• 页码：1198-1201
• 全文大小：372K
• ISSN：1523-7052

文摘

A flow process for N-Heterocyclic Carbene (NHC)-mediated anodic oxidative amidation of aldehydes is described, employing an undivided microfluidic electrolysis cell to oxidize Breslow intermediates. After electrochemical oxidation, the reaction of the intermediate N-acylated thiazolium cation with primary amines is completed by passage through a heating cell to achieve high conversion in a single pass. The flow mixing regimen circumvented the issue of competing imine formation between the aldehyde and amine substrates, which otherwise prevented formation of the desired product. High yields (71–99%), productivities (up to 2.6 g h^–1), and current efficiencies (65–91%) were realized for 19 amides.