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Paper | Regular issue | Vol 65, No. 3, 2005, pp.579-589
Published online, 25th January, 2005
DOI: 10.3987/COM-04-10291
Synthesis of 2-Substituted Thiopyrano[3,2-b][1,4]benzoxazine-2,3-dicarboxylic Acid Dimethyl Esters

Sukanta Kamila, Hongming Zhang, Dumming Zhu, and Edward R. Biehl*

*Southern Methodist University, Department of Chemistry, Dallas, TX 75275, U.S.A.


The titled compounds were prepared by the reaction of 4H-benzo[1,4]oxazin-3-thiones with dimethyl acetylenedicarboxylate. The 3-thione intermediates were obtained by treating 4-methyl-4H-benzo[1,4]oxazin-3-ones with P2S5 followed by piperidine-mediated condensation of the resulting 4-methyl-4H- benzo[1,4]oxazin-3-thiones with various aromatic and heteroaromatic aldehydes. Oxazine-3-thiones, however, failed to react with several benzyne intermediates.