Preparation of New Nitrogen-Bridged Heterocycles. 36. Synthesis and Reaction of Dimethyl 4-Thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-diene-5,6-dicarboxylate Derivatives

Abstract

Abstract The title compounds, dimethyl 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-diene-5,6-dicarboxylates, were prepared in low to moderate yields by the reactions of various 1-pyridinio[(thiocarbonyl)methylide]s and 3-(1-pyridinio)thiophene-2-thiolates with dimethyl acetylenedicarboxylate in chloroform or benzene at room temperature or at the elevated temperature. Some compounds could also be obtained by heating the corresponding dimethyl 10aH-pyrido[1,2-d][1,4]thiazepine-1,2-dicarboxylates once separated from the reaction of pyridinium ylides with the same reagent. These 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-diene derivatives were smoothly thermolyzed in xylene at the reflux temperature to afford dimethyl phthalate and the corresponding thiazole derivatives in good yields. The structures of these 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-dienes were mainly identified by their physical and spectral inspections together with mechanistic considerations, and confirmed finally by the X-ray analyses of two compounds.