Iron-catalyzed [3 + 2 + 1] annulation of 2-aminobenzimidazoles/3-aminopyrazoles and aromatic alkynes using N,N-dimethylaminoethanol as a one carbon synthon for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrimido[1,2-b]indazoles was written by Qin, Zemin;Zhang, Ruiqin;Ying, Shenpeng;Ma, Yongmin. And the article was included in Organic Chemistry Frontiers in 2022.Application In Synthesis of 2-Ethynylthiophene This article mentions the following:
A simple and efficient method for the synthesis of pyrimido[1,2-a]benzimidazoles I (R = R1 = H, Cl; R2 = Ph, 1-naphthyl, 2-thienyl, etc.; R3 = H, Me, Ph, thiophen-3-yl, etc.) and pyrimido[1,2-b]indazoles II (R4 = H, Cl, F; R5 = H, Me, Br) from 2-aminobenzimidazoles/3-aminoindazoles, alkynes R2CCR3 and N,N-dimethylaminoethanol by a three-component [3+2+1] annulation catalyzed by FeCl3 has been established, where N,N-dimethylaminoethanol was applied as a methine source. Good tolerance of the reaction makes this method applicable to construct biol. active pyrimido[1,2-a]benzimidazoles and pyrimido[1,2-b]indazoles. In addition, regioselective aryl substituted pyrimido[1,2-a]benzimidazoles were synthesized in the presence of TfOH. Replacement of alkynes with acetaldehydes gave the same pyrimido[1,2-a]benzimidazoles and pyrimido[1,2-b]indazoles. In the experiment, the researchers used many compounds, for example, 2-Ethynylthiophene (cas: 4298-52-6Application In Synthesis of 2-Ethynylthiophene).
2-Ethynylthiophene (cas: 4298-52-6) belongs to benzothiophene derivatives. Benzothiophene scaffolds are of great importance due to its increased presence in bioactive molecules. It is found within the chemical structures of pharmaceutical drugs such as raloxifene, zileuton, and sertaconazole, and also BTCP.Application In Synthesis of 2-Ethynylthiophene
Referemce:
Benzothiophene – Wikipedia,
Benzothiophene | C8H6S – PubChem