|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1994 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1993 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Heterocyclic compounds such as pyrrole, pyrimidine, purine and pyridine occur in living systems and important in view of their potential biological activity. In the course of our study of the utilization of organoselenium compounds we were interested to find that 1,2,5-selenadiazole reacts in an uncommon way with 1,3-diketones to provide a novel synthesis of a variety of 2,3,4,5-substituted pyrroles. The synthesis of pyrroles is so far restricted to a small number of classical methods. Here we report a one-pot synthesis of pyrroles from 1,2,5-selenadiazole and 1,3-diketones.
4-Methyl-3-phenylcarbamoyl-1,2,5-selenadiazole a compound we obtained earlier by an intriguing transformation with selenium dioxide from 5-amono-6-methyl-3-phenylpyrimidine-4 (3H) -one was thought likely to be easily reduced to give a diamine, which might then react with 1,3-diketones such as acetylacetone or benzoylacetone, to give diazepines. Thus, the reaction of the compound with acetylacetone in isopropyl alcohol in the presence of zinc dust and acetic acid was examined. Unexpectedly, 3-acetyl-2,4-dimethyl-5-phenylcarbamoylpyrrole accompanied by small amount of 2,4-dimethyl-5-phenylcarbamoylpyrrole were formed, structural assignments for the two compounds being based on spectral evidence(lR,^1H NMR and mass). Similar reaction with acetoacetanilide, ethyl acetoacetate, benzoylacetone and 3-methylpentane-2,4-dione gave corresponding pyrroles. In contrast, in its reaction with dibezoylacetone the compound afforded, solely, 2,5-dimethyl-3,6-bis (phenyl-carbamoyl) pyrazine rather than a pyrrole.