Lalezari, Iradj et al. published their research in Journal of Heterocyclic Chemistry in 1979 | CAS: 70291-62-2

2-Amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carbonitrile (cas: 70291-62-2) belongs to nitriles. Nitrile carbon shifts are in the range of 115–125 ppm whereas in isonitriles the shifts are around 155–165 ppm. In addition, Nitriles can react with alkynes, which leads to an increase in carbon chain length (carbocyanation).Recommanded Product: 70291-62-2

Synthesis of 4-aminothieno[2,3-b]pyridine-5-carboxylic acids was written by Lalezari, Iradj. And the article was included in Journal of Heterocyclic Chemistry in 1979.Recommanded Product: 70291-62-2 This article mentions the following:

The title compounds I [R = R1 = Me or RR1 = (CH2)n, n = 3,4,5] were prepared in ∼80% yields by condensing 2-amino-3-cyanothiophenes with Et 3-aminocrotonate in the presence of p-MeC6H4SO3H, EtONa-catalyzed cyclization of the resulting II, and hydrolysis. In the experiment, the researchers used many compounds, for example, 2-Amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carbonitrile (cas: 70291-62-2Recommanded Product: 70291-62-2).

2-Amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carbonitrile (cas: 70291-62-2) belongs to nitriles. Nitrile carbon shifts are in the range of 115–125 ppm whereas in isonitriles the shifts are around 155–165 ppm. In addition, Nitriles can react with alkynes, which leads to an increase in carbon chain length (carbocyanation).Recommanded Product: 70291-62-2

Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts