Recently, we developed a rapid procedure for the Leuckart reaction and successfully applied it for the synthesis of substituted N-benzyl- N-methylformamides. Interestingly, in the reaction conducted on 4-chlorobenzaldehyde, a large amount of a by-product, N, N-di-(4-chlorobenzyl)- N-methylamine was produced with an isolated yield of 31.3%. N-(4-chlorobenzyl)- N-methylformamide was produced with an isolated yield of 52.0%. It was interesting to determine what results the reaction will produce with 4-bromobenzaldehyde. We hypothesized that the ratio of the products depends on the nature of the substituents and that lower electronegativity of bromine will result in a higher yield of the dibenzyl product and a lower yield of the monobenzyl product compared to the yields of the respective products in the reaction with 4-chlorobenzaldehyde. The reaction was conducted on 10 mmol scale at 186oC. Column chromatography was used for the isolation of the products of the reaction. NMR-spectroscopy and elemental analysis were used to determine the structures of the products. The reaction was fully completed in 5 minutes. As expected, the isolated yields of N, N-di-(4-bromobenzyl)-N-methylamine (36.3%) and N-(4-bromobenzyl)-N-methylformamide (47.6%) appeared to be approximately 5% higher and 5% lower than the yields of the respective products in the previous reaction. The reaction comprises a new method for the synthesis of N-(4-bromobenzyl)-N-methylformamide and N,N-di-(4-bromobenzyl)-N-methylamine. The project was supported by NIH grant 8 P20 GM103442-12 from the National Institute of General Medical Sciences.

Rapid synthesis of N-(4-bromobenzyl)-N-methylformamide

253rd National Meeting (2017)

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