Substitution reactions of benzo[b]thiophene derivatives. Part VIII. Reactions of some 6-substituted compounds and of 4-chlorobenzo[b]thiophene and its 3-methyl derivative was written by Clark, Peter D.;Clarke, Kenneth;Scrowston, Richard M.;Sutton, Terence M.. And the article was included in Journal of Chemical Research, Synopses in 1978.Formula: C8H5ClS This article mentions the following:
Electrophilic substitution reactions (e.g., nitration, bromination, Friedel-Crafts acetylation) of the benzothiophene derivatives I (R = NHAc, OH, Me, Cl, R1 = R2 = H; R = Cl, R1 = Me, R2 = H; R = H, R1 = H, Me, R2 = Cl) were studied and new methods for the preparation of I (R = Cl, R1 = Me, R2 = H; R = H, R1 = H, Me, R2 = Cl) described. For I (R = NHAc, OH, R1 = R2 = H), the 2- and 7-positions are the most reactive in nitration and bromination although some substitution in the 5-position also occurred. For I (R = NHAc, R1 = R2 = H), Friedel-Crafts acetylation occurred in the 2- and 3-positions; Vilsmeier-Haack formylation gave either the N-formyl derivative or the amidine I (R = N:CHNMe2, R1 = R2 = H), depending on the temperature I (R = Me, R1 = R2 = H) gave a mixture of the 2- and 3-substituted products (∼1:1) on nitration and bromination, but gave the 2-acetyl compound exclusively on acetylation. Substitution in I (R = Cl, R1 = H, Me, R2 = H) was confined to the 3- and 2-position resp., except that the former gave a mixture of the 2- and 3-acetyl derivatives on acetylation. I (R = H, R1 = H, Me, R2 = Cl) were both acetylated in the 2-position; the former gave a mixture of 2- and 3-substitution products on nitration and bromination. Bromination of I (R = H, R1 = Me, R2 = Cl) was confined to the Me group; nitration gave a mixture of the 2-nitro compound and the thiophenone II. In the experiment, the researchers used many compounds, for example, 6-Chlorobenzothiophene (cas: 66490-20-8Formula: C8H5ClS).
6-Chlorobenzothiophene (cas: 66490-20-8) belongs to benzothiophene derivatives. Benzothiophene is relatively a stable molecule. The electrophilic substitution of benzothiophene systems is much less regioselective than that of indoles. It is found within the chemical structures of pharmaceutical drugs such as raloxifene, zileuton, sertaconazole, and also BTCP.Formula: C8H5ClS
Referemce:
Benzothiophene – Wikipedia,
Benzothiophene | C8H6S – PubChem