An imidate is a compound containing a carbon-nitrogen double bond. Many imidates can serve as intermediates in the synthesis. The study of imidates’ properties and reactions has also been of concern to everyone.
Reduction reaction: Reduction of the imidate salt with sodium amalgam and dilute mineral acid provides the aldehyde. According to Henle, this reaction is one of the best to obtain the aldehyde in the form of its hydrazone in the presence of a substituted hydrazine. In addition, 5-methyl-3,3-diphenyl-2-tetrahydrofuranimine, which contains an imidate within the ring, is smoothly reduced to amino alcohol by the same reagent.
Condensation reaction: Knott demonstrated that the ethyl N-phenylimidate can condense with the mono- and polymethylpyridines to produce compound with anilinovinyl group. Due to their reactivity with the reactive methylene groups in the ring system, heterocyclic systems have also been found to condense with reagent. Studies on trinuclear cyanine dyes have also led to observation of the condensation reaction of thiazolines and benzothiazolines containing methylene groups in the presence of zinc chloride. The condensation of the imidate base with the sulfonyl halide produces the sulfonyl derivative of imidate. The reaction is carried out in the presence of two moles of imidate and one halide; the amides are formed simultaneously.
Oxidation reaction: Ethyl N-benzylthioanilinate is oxidized to a substituted amide by selenium dioxide or iodine in alcohol. Atmospheric oxygen can also convert the same imidate to benzamide.
Reaction with Grignard reagent: The reaction with phenylmagnesium bromide in toluene gives the substituted ketimine and then treats the benzophenone with acid. A series of substituted ketols are prepared by the reaction of Grignard reagents with mandelimidate and ethyl atrolactimidate or its hydrochloride, in a yield comparable to the synthesis of these compounds with the corresponding amides. In addition, benzoin is synthesized from mandelimidate and phenylmagnesium bromide. Unlike the addition reaction formulated as the first stage of the reaction between the amide and the Grignard reagent, the following substitution mechanism has been proposed in the presence of imidate.
Fig.1. Mechanism of reaction between the amide and the Grignard reagent