Aminomethylation of organic halides promoted by zinc in protic medium

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• 作者：Idá ; lia H.S. Estevam ; Margarete F. da Silva and Lothar W. Bieber
• 关键词：Mannich reaction ; Aqueous formaldehyde ; Alkyl halides ; Radical mechanism
• 刊名：Tetrahedron Letters
• 出版年：2005
• 期刊代码：109_00404039
• 类别：ch
• 出版时间：2005
• 卷：46
• 期：44
• 页码：7601-7604
• 文件大小：109 K

摘要

Organic halides undergo smooth aminomethylation by secondary amines and aqueous formaldehyde promoted by metallic zinc under copper(I) catalysis. Good to excellent yields are obtained with primary, secondary, and tertiary iodides, allylic, propargylic, and benzylic bromides and with α-bromoesters. In most cases, DMSO is the best solvent, but dioxane is preferable for some more reactive halides. Additional experiments with radical quenchers and promoters and the use of ‘radical clocks’ indicate a stepwise reaction mechanism initiated by the attack of an alkyl radical to iminium ion.