Monocyclic thiabenzenes, 1-alkyl-2-aroyl- (or 1-alkyl-2-cyano-) 4,5-dimethylthiabenzenes () are successfully synthesized by deprotonation of the corresponding thiopyranium salts () with triethylamine in ethanol. The ylide structures of are elucidated by spectral and chemical evidence. Thermal reaction of in several solvents provides S-alkyl rearranged products and ring-contracted ones, depending upon
Synthesis and thermal transformation of stable monocyclic λ4-thiabenzenes
作者:Hiroshi Shimizu、Noriaki Kudo、Tadashi Kataoka、Mikio Hori
DOI:10.1039/b102806p
日期:——
The stable monocyclic λ4-thiabenzenes 6aâe, which are stabilized with electron-withdrawing substituents such as benzoyl, cyano and alkoxycarbonyl groups, are synthesized in high yields by proton abstraction from the corresponding thiopyranium salts 5aâe with triethylamine in ethanol. The ylidic properties of the λ4-thiabenzenes are established based on spectral and chemical evidence. Thermal decomposition of the λ4-thiabenzenes affords alkyl-rearranged products 7, 8, and 9, thienofuran derivatives 10 (from benzoyl-substituted λ4-thiabenzenes), and thiophene derivatives 11. A plausible mechanism for the formation of those products is also discussed.