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Short Paper | Regular issue | Vol 83, No. 7, 2011, pp.1641-1647
Published online, 18th May, 2011
DOI: 10.3987/COM-11-12227
A Convenient Synthesis of 1,3-Disubstituted 4-Thioxo-3,4-dihydropyrido[2,3-d]pyrimidin-2(1H)-ones and 4-Thioxo-3,4-dihydropyrido[4,3-d]pyimidin-2(1H)-ones

Kazuhiro Kobayashi,* Toshihide Komatsu, Yuki Yokoi, and Hisatoshi Konishi

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

Abstract

The reaction of 2-chloro-3-lithiopyridine with alkyl isothiocyanates gave the corresponding N-alkyl-2-chloropyridine-3-thiocarboxamides, which in turn were allowed to react with aryl isocyanates in the presence of sodium hydride as a base to give 3-alkyl-1-aryl-4-thioxo-3,4-dihydropyrido[2,3-d]pyrimidin- 2(1H)-ones. A similar sequence starting from 4-chloro-3-lithiopyridine and ethyl isothiocyanate gave 1-aryl-3-ethyl-4-thioxo-3,4-dihydropyrido[4,3-d]pyrimidin- 2(1H)-ones, via 4-chloro-N-ethylpyridine-3-thiocarboxamide.