Benzothiophens and their Benzo-fused Systems

Synthesis of Benzothiophens by Ring-closure Reactitms.— Thiophenols react slowly (5-22 days) with dimethyl acetylenedicarboxylate in methanol to 

A new important route to the benzo[c]thiophen series was found in the reaction of (278) with alkali, yielding (279). Complexes obtained from 

Heating of (280) with acetic anhydride proceeds with elimination of the t-butyl group, giving dibenzothiophen. Condensation of (281) with (282) 

Sugawara, H. Masuya, T. Matsuo, and T. Miki, Chem. Pharm. Bull., 1979, 27, 3095. 

Kawano, T. Watanabe, J. Sakai, H. Watanabe, M. Nagano, T. Nishimura, and T. Miyadera, Chem. Pharm. Bull, 1980, 28, 70. 

Kataoka, M. Yoshioka, Y. Sendo, Y. Nishitani, S. Hirai, T. Maeda, and W. Nagata, Tetrahedron Lett., 1979, 2793. 

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