ABSTRACT Several azapropenylium salts, such as 1-chloro-1,3-bis(dimethylamino)-3-phenyl-2-azaprop-2-en-l-ylium perchlorate, obtained from the reaction of phosphorus oxychloride-tertiary amide complex and dimethylcyanamide are prepared and characterized. They are found to react with simple amines viz hydrazine and hydroxylamine to form five-membered rings 1,2,4-triazole and 1,2,4-oxadiazole, respectively. The reaction with 1,1,3,3-tetramethylquanidine yielded the six-membered fully conjugated pyrimidine, frequently, via isolable diazahexadienylium intermediates. Similarly the reaction involving secondary amides gave diazabutyenylium salts, such as 1-chloro-4-methyl-1-dimethylamino-3-phenyl-2,4-diazabut-3-en-1-ylium perchlorate, which afforded 1,3,5-triazinium perchlorates via, in most cases, isolable acyclic triazahexadienyluim compounds. Each of the intermediates reacted with 2-amino-4-methylpyridine to yield 2-membered ring condensed 8-methyl-4-dimethylamino-2-phenylpyrido[1,2-a]-1,3,5-triazinium perchlorate whose unequivocal structure was established by X-ray crystallography and refinement. Various suitably substituted pyridines reacted similarly to afford the corresponding pyrido[1,2-a]-1,3,5-triazinium salts. The limitations of this procedure were extensively investigated. A wide variety of condensed 1,3,5-triazinium perchlorates were obtained when several suitably substituted heterocyclic compounds were treated either with the azapropenylium or diazabutenylium salts.
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