A New Synthesis of Cinnamic Acids from Aromatic Aldehydes and N,n-dimethylacetamide Hydrochloride

Thorough studies of organic chemistry have emphasized the important role of reactive solvents in some condensation reactions, such as ethynylation of carbonylic compounds. Some of the most widely used reactive solvents for these reactions are N,N-dialkylacetamides, among which N,N-dimethylacetamide is prominent due to its particular reactivity. This is the reason why it had been used not only as solvent and reaction medium, but also as a very effective catalyst and, in the case of N,N-dimethylacetamide hydrochloride, even as a reagent. As a general feature, these reactive solvents are able to yield in compounds which result from a condensation reaction at the methylene group in α position towards amide moiety, position activated by the presence of an electron withdrawing functional group (-E). The reactions of N,N-dimethylacetamide with aromatic ketones in the presence of strong bases such as potassium hydroxide (KOH) or sodium amide (NaNH2) as condensing agents are known. Therefore, we considered of interest to study the condensation reaction of N,N-dimethylacetamide and aromatic aldehydes in the presence of a strong acid, such as hydrochloric acid (HCl). On the other hand, the cinnamic acid and its derivatives, as reagents for organic and macromolecular chemistry, due to their photoreactive