Substitution reactions of 2- and 3-methylthianaphthene was written by Shirley, David A.;Danzig, Morris J.;Canter, Frank C.. And the article was included in Journal of the American Chemical Society in 1953.Formula: C9H7BrS This article mentions the following:
2-Methylthianaphthene (I) in 30 cc. CHCl3 (ice bath) treated dropwise with Br in CHCl3 yielded 7.0 g. 2-methyl-3-bromothianaphthene (II), m. 42-2.5°. II converted to the Grignard reagent (considerable MeI required to initiate the reaction) and carbonated yielded 50% 2-methyl-3-thianaphthenecarboxylic acid (III), m. 194-5°. III was desulfurized to α-phenylbutyric acid, m. 33.5-35°; amide, m. 85-6°. I (10 g.) in 65 cc. AcOH (ice bath) treated during 5 min. with 30 cc. concentrated HNO3, the mixture let stand 30 min. in the ice bath and filtered yielded 5.75 g. 2-methyl-3-nitro-thianaphthene (IV), m. 98-8.5°. IV (5 g.) reduced in AcOH-Ac2O over Raney Ni at 50 lb./sq. in. H yielded 2.73 g. 2-methyl-3-acetamidothianaphthene (V), m. 186-6.5°. Desulfurization of V yielded N-acetyl-1-phenylpropylamine, m. 77-8°. 3-Methylthianaphthene (VI) (6.6 g.) in 30 cc. Et2O treated slowly with 0.045 mol BuLi in Et2O, the mixture refluxed 45 min., carbonated with Dry Ice, hydrolyzed, treated with dilute HCl, and the Et2O extracts evaporated yielded 5.1 g. 3-methyl-2-thianaphthenecarboxylic acid (VII), m. 244.5-46°. VII treated with SOCl2 and the acid chloride with NH3 yielded 70% of the amide (VIII), m. 181-3°. Desulfurization of VIII yielded 85% β-phenylbutyramide, m. 105-6°; p-nitro derivative, m. 164°. VI (5 g.) in 10 cc. AcOH treated with 10 cc. each of HNO3 and AcOH, the mixture let stand 15 h. at room temperature, and poured into water yielded 1.65 g. 2-nitro-3-methylthianaphthene (IX), m. 148-9°. Reduction of IX gave 55% of the acetamido (X) compound, m. 182.5-83°, which on alk. hydrolysis gave 2-phenylpropylamine; picrate, m. 184-5°; N-Bz derivative, m. 87.5-88°. IX in Et2O reduced over Raney Ni at 50 lb./sq. in., the Et2O evaporated, and the residue treated with BzCl and alkali yielded 2-benzamido-3-methylthianaphthene, m. 167.5-70°. In the experiment, the researchers used many compounds, for example, 3-Bromo-2-methylbenzo[b]thiophene (cas: 10243-15-9Formula: C9H7BrS).
3-Bromo-2-methylbenzo[b]thiophene (cas: 10243-15-9) 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, and sertaconazole, and also BTCP.Formula: C9H7BrS
Referemce:
Benzothiophene – Wikipedia,
Benzothiophene | C8H6S – PubChem