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Short Paper | Regular issue | Vol 87, No. 4, 2013, pp.885-895
Published online, 6th March, 2013
DOI: 10.3987/COM-13-12677
■ Synthesis of 7H-Thiopyrano[2,3-d]pyrimidines by Hydrobromic Acid-Mediated Cyclization of 1-[4-(1,1-Dimethylethylsulfanyl)pyrimidin-5-yl]prop-2-en-1-ols

Kazuhiro Kobayashi,* Teruhiko Suzuki, Ayumi Imaoka, 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

7-Aryl- or 5,7-diaryl-4-methoxy-2-methylsulfanyl-7H-thiopyrano[2,3-d]pyrimidines have been prepared in satisfactory overall yields starting from 4-chloro-6-methoxy-2-(methylsulfanyl)pyrimidine by a facile three-step sequence. 4-Chloro-5-lithio-6-methoxy-2-(methylsulfanyl)pyrimidine was generated by the treatment of 4-chloro-6-methoxy-2- (methylsulfanyl)pyrimidine with LDA and was allowed to react with 3-arylprop-2-enals (cinnamaldehyde and its derivatives) or 1,3-diarylprop-2-en-1-ones (chalcone and its derivatives) to give the corresponding 3-aryl- or 1,3-diaryl-1-(4-chloropyrimidin-5-yl)prop-2-en-1-ol derivatives, respectively. Substitution of the 4-chloro group with sodium 1,1-dimethylethylthiolate gave 3-aryl- or 1,3-diaryl-1-[4-(1,1-dimethylethylsulfanyl)-pyrimidin-5-yl]prop-2-en-1-ol derivatives, of which treatment with an equivalent of hydrobromic acid provided the desired products.