Promotion effects of Lewis acid/(CH3)4NI on [Co(CO)4]ˉ-catalyzed C–N bond activation in the carbonylation of trimethylamine

• Lewis acid and (CH3)4NI were used to promote carbonylation of trimethylamine.
• High activity of NaCo(CO)4 was obtained under relatively mild reaction conditions.
• Excellent selectivity and yield of N,N-dimethylacetamide were obtained.
• The catalytic mechanism was proposed.

An effective synthesis of N,N-dimethylacetamide (DMAc) via NaCo(CO)4-catalyzed carbonylation of trimethylamine is reported. Lewis acid (AlCl3, FeCl3, BiCl3, InCl3 etc.) and (CH3)4NI were used as promoters to activate the unreactive sp3 carbon–nitrogen (C–N) bond of trimethylamine and a significant increase in catalytic activity was observed. High selectivity (98%) and yield of DMAc (96%) were obtained under relatively mild reaction conditions. Based on the role of promoters and the products in the reaction, a plausible mechanism that contains two different ways of activating C–N bond was proposed.

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