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Short Paper | Regular issue | Vol 89, No. 8, 2014, pp.1933-1939
Published online, 30th June, 2014
DOI: 10.3987/COM-14-13038
A Simple Method for the Preparation of Pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-dithione Derivatives

Kazuhiro Kobayashi,* Minami Kuroda, Noriyuki Tanaka, Yuki Yokoi, Akihiro Kobayashi, Hidetaka Hiyoshi, and Kazuto Umezu

*Division of Applied Chemistry, Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

A facile and efficient two-step sequence for the preparation of 1,3-disubstituted pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-dithiones starting with 4-chloro-6-methoxy-2-(methylsulfanyl)pyrimidine has been developed. Thus, the reaction of 4-chloro-5-lithio-6-methoxy-2-(methylsulfanyl)pyrmidine, generated by the treatment of the starting material with lithium diisopropylamide (LDA), with some aliphatic isothiocyanates gives N-alkyl-4-chloro-6-methoxy-2- (methylsulfanyl)pyrimidine-5-carbothioamides, which are then allowed to react with various isothiocyanates in the presence of sodium hydride to give the desired products. This method is applicable to the synthesis of 1,3-disubstituted 4-thioxo- 3,4-dihydropyrimido[4,5-d]pyrimidin-2(1H)-ones using phenyl isocyanate in place of isothiocyanates.