Background: 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%. The ratio of the yield of the dibenzyl product to the yield of the monobenzyl product was 1:1.66. Hypothesis: The reaction conducted on benzaldehydes with electron-donating substituents may produce higher yields of the respective N,N-dibenzyl-N-methylamines and lower yields of the respective N-benzyl-N-methylformamides. In this work the hypothesis was tested by conducting the reaction on 4-methoxybenzaldehyde. Methods: The reaction was conducted on 10 mmol scale at 187-189°C. Column chromatography was used for the isolation of the products. NMR-spectroscopy and elemental analysis were used to determine the structures of the products. Results: The reaction was completed in 10 minutes. Both the isolated yield of N,N-di-(4-methoxybenzyl)-N-methylamine (31.3%) and the isolated yield of N-(4-methoxybenzyl)-N-methylformamide (49.3%) appeared to be very close to the isolated yields of the respective products in the reaction with 4-chlorobenzaldehyde. The ratio of the yields shifted only slightly, from 1:1.66 to 1:1.58. Conclusions: The results of the first trial reaction do not agree with the initial hypothesis. Further conclusions will be made after the reaction is replicated. The reaction provides a new method for the synthesis of N-(4-methoxybenzyl)-N-methylformamide and N,N-di-(4-methoxybenzyl)-N-methylamine.

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

2019 Spring National Meeting

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