The formylation of perimidine, its 2-and 3-methyl derivatives, and 2,2-dimethyl-2,3-dihydroperimidine has been studied under the conditions of the Vilsmeier reaction. In the last case recyclization occurs. The characteristics of the 1 H NMR spectra of the aldehydes obtained are discussed.In a continuation of an investigation of the formylation of perimidones, 2,3-dihydroperimidines, and 2-trifluoromethylperimidines [2], we have attempted to study the effect of the Vilsmeier reagent on perimidine and its simple derivatives. We have discovered, however, that they are formylated with considerably more difficulty than perimidones and 2,3-dihydroperimidines. For example, in the case perimidine (1) or 2-methylperimidine (2) a considerably greater amount of the Vilsmeier reagent than usual was required and the reaction only began at 80-90°C. The reaction occurred unexpectedly with the formation of poorly soluble oligomeric substances ( 1 H NMR data) from which the required monoaldehydes were separated with considerable difficulty. The basic products in the case of perimidine were 4(9)-3 and 6(7)-carbaldehydes 4 the yields of each of which did not exceed 10%. Formylation of 2-methylperimidine occurred with even greater difficulty: the yields of the 4(9)-aldehyde 5 and the 6(7)-aldehyde 6 were ~2 and 1% respectively. A considerable amount of the starting materials was regenerated.

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