Dihydropyrimidines as Precursors for Synthesizing of Oxoketene gem-Dithiol and 1,2-Dithiol-3-Thione, a Facile Synthesis and Convenient Reaction Transformations

Abstract

In the present work the authors could synthesize the substrates oxoketen gem-dithols 5, ketenedithioacetal 6 and 1,2-dithiol-3-thione 39 from compounds bearing both nucleus indole and dihydropyrimidines together due to their biological and pharmacological activities. In this paper, and as a result of biological and pharmacological activities of oxoketen gem-dithols, ketenedithioacetal and/or 1,2-dithiol-3-thione; we synthesized various derivatives of them via indole and dihydropyrimidine in the form of either condensed or fused derivatives. We used ecofriendly methods such as pure orange juice as a green solvent and as an acid catalyst in the same time to prepare, 1-[2-imino-4-(1H-indol-3-yl)-6-methyl-1,2,3,4-tetrahydropyrimidin-5-yl]-ethan-1-one 4a and/or 1-[4-(1H-Indol-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl]-ethan-1-one 4b. Subsequently, the substrate 4b was treated with different reagents to afford, 1-(4-(1H-indol-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-3,3-dimercaptoprop-2-en-1-one 5 and/or 1-(4-(1H-indol-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-3,3-bis(methylthio)prop-2-en-1-one 6. Compounds 5 and/or 6 were used as synthons to get various heterocyclic compounds such as 3-(4-(1H-indol-3-yl)-6-methyl-2-(piperidin-1-yl)-1,4-dihydropyrimidine-5-carbonyl)-2-thioxochroman-4-one 16 and/or 4'-(1H-indol-3-yl)-2-mercapto-6'-methyl-6-(methylthio)-2'-thioxo-1',2',3',4'-tetr-ahydro-[4,5'-bipyrimidin-e]-5-carbaldehyde 18. The newly synthesized compounds have been in vitro examined as antimicrobial agents, and some of them showed a promising activity. All newly synthesized compounds have been characterized by means of elemental analyses, IR, 1H-NMR and MS.