Aminomethylation of organic halides promoted by zinc in protic medium |
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Authors: | Idá lia H.S. Estevam,Margarete F. da Silva |
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Affiliation: | a Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, 50670-901 Recife, PE, Brazil b Departamento de Ciências Exatas e da Terra, Universidade do Estado da Bahia, Cabula, 40000-000 Salvador, BA, Brazil |
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Abstract: | 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. |
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Keywords: | Mannich reaction Aqueous formaldehyde Alkyl halides Radical mechanism |
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