Synthesis of 4- and 6-methyl derivatives of 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-<i>d</i>]pyrimidine based on methylbarbituric acids, spectroscopic characteristics and acidity constants
Abstract
We have obtained previously unknown 1-methyl- and 1,3-dimethyl-5-diethylaminothiocarbonylthiobarbituric acids by reaction of sodium diethyldithiocarbamate with 5-phenyliodonium betaines of 1-methyl- and 1,3-dimethylbarbituric acids. Cyclization of these compounds upon heating in conc. H2SO4 gives methyl-substituted 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2-diethylimmonium hydrosulfates; the derivative of 1-methylbarbituric acid forms a mixture of 4-methyl- and 6-methyl-substituted compounds (2∶1). We isolated perchlorates of 4-methyl- and 4,6-dimethyl-substituted derivatives in pure form. By treatment of the immonium salt with sodium sulfide or selenide, we obtained 4-methyl- and 4,6-dimethyl-5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2-thiones and 4-methyl-, 6-methyl-, and 4,6-dimethyl-2-selenones. We characterized the isomeric 4- and 6-methyl-substituted selenones by electronic absorption spectra and ionization constants (7.65 and 4.0). The differences in the pK values and in the electronic absorption spectra makes it possible to distinguish the substitution site in N-mono-substituted derivatives of 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine.
How to Cite
Neiland, O. Ya.; Adamsone, B. Ya.; Dureya, R. Yu.; Gudele, I. Ya.; Zagorskaya, N. N. Chem. Heterocycl. Compd. 1993, 29, 1308. [Khim. Geterotsikl. Soedin. 1993, 1526.]
For this article in the English edition, see DOI https://doi.org/10.1007/BF00532032
