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Short Paper | Regular issue | Vol 96, No. 4, 2018, pp.757-765
Published online, 13th March, 2018
DOI: 10.3987/COM-18-13879
A Facile Synthesis of 1,4-Dihydro-2H-pyrimido[4,5-d][1,3]oxazin-2-one Derivatives from 4,6-Dichloro-2-(methylsulfanyl)pyrimidine

Kazuhiro Kobayashi,* Yuka Tsunomori, Takashi Nogi, Hidetaka Hiyoshi, and Kazuto Umezu

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


A facile three-step sequence has been developed for the preparation of 1,4-dihydro-2H-pyrimido[4,5-d][1,3]oxazin-2-one derivatives from 4,6-dichloro-2-(methylsulfanyl)pyrimidine (DCSMP) under mild conditions. Thus, the starting material is treated with LDA to generate the 5-lithiated compound, which is then allowed to react with (het)aromatic and aliphatic aldehydes to give the corresponding 1-[4,6-dichloro-2-(methylsulfanyl)pyrimidin-5-yl]alkan-1-ols. The reaction of these compounds with primary amines in the presence of triethylamine gives 1-[4-(alkylamino)-6-chloro-2-(methylsulfanyl)pyrimidin-5-yl]alkan-1-ols, of which subjection to successive treatment with an equimolar amount each of sodium hydride and ethyl chloroformate provides the desired 1,4-disubstituted 7-(methylsulfanyl)-1,4-dihydro-2H-pyrimido[4,5-d][1,3]oxazin-2-ones.