Hetero-Type Benzannulation Leading to Substituted Benzothio-Phenes

TiCl(4) (or SnCl(4))-promoted hetero-type benzannulation reactions using various (2,2-dichlorocyclopropyl)(thiophen-2-yl)methanols proceeded smoothly to produce uniquely substituted 4-chlorobenzothiophenes (five examples). The present approach involves the first distinctive thiophene formation from...

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Detalles Bibliográficos
Autores principales: Kono, Taro, Sasaki, Ryosuke, Goto, Hideki, Kakuno, Masatoshi, Tanabe, Yoo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Article
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8620883/
https://www.ncbi.nlm.nih.gov/pubmed/34834100
http://dx.doi.org/10.3390/molecules26227008
Descripción
Sumario:TiCl(4) (or SnCl(4))-promoted hetero-type benzannulation reactions using various (2,2-dichlorocyclopropyl)(thiophen-2-yl)methanols proceeded smoothly to produce uniquely substituted 4-chlorobenzothiophenes (five examples). The present approach involves the first distinctive thiophene formation from thiophene cores, in contrast to traditional methods of thiophene formation from benzene cores. The stereocongested (less reactive) Cl position in the obtained 4-chlorobenzothiophenes functioned successfully as the partners of three cross-coupling reactions: (i) a Suzuki–Miyaura cross-couplings using Pd(OAc)(2)/SPhos/K(3)PO(4) catalysis (seven examples; 63–91%), (ii) a hydroxylation using KOH/Pd(dba)(2)/tBu-XPhos catalysis (85%), and (iii) a borylation using a B(2)(pin)(2)/Pd(dba)(2)/XPhos/NaOAc catalysis-provided 4-(pin)B-benzothiophene (58%).

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