Recently, we developed a rapid procedure for the synthesis of substituted N-benzyl-N-phenylformamides. Interestingly, in the reaction conducted on 4-nitrobenzaldehyde, a large amount of a by-product, N,N-di-(4-nitrobenzyl)-N-phenylamine was produced with an isolated yield of 38.8%. N-(4-nitrobenzyl)-N-phenylformamide was produced as the main product with an isolated yield of 49.9%. The ratio between the monobenzyl and the dibenzyl products is determined by the balance of the electron-withdrawing and electron-donating properties of the substituents. Consequently, in the reaction with 2,4-dichlorobenzaldehyde, the ratio between the dibenzyl product, N,N-di-(2,4-dichlorobenzyl)-N-phenylamine, and the monobenzyl product, N-(2,4-dichlorobenzyl)-N-phenylformamide, will remain close to the ratio of the respective products in the reaction with 4-nitrobenzaldehyde.<br/>The reaction was conducted on a 10 mmol scale at 180-210°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.<br/>The reaction was completed in 20 minutes. The isolated yields of N,N-di-(2,4-dichlorobenzyl)-N-phenylamine and N-(2,4-dichlorobenzyl)-N-phenylformamide were 33.2% and 52.8%, respectively. The ratio of the yield of the dibenzyl product to the yield of monobenzyl product shifted slightly from 0.78:1 to 0.63:1. The results of the reaction support the initial hypothesis. The reaction provides a new method for the synthesis of N-(2,4-dichlorobenzyl)-N-phenylformamide.

Rapid synthesis of N-(2,4-dichlorobenzyl)-N-phenylformamide

ACS Spring 2022

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