Design, Synthesis and Aromaticity of an Alternating Cyclo[4]Thiophene[4]Furan.
Chemistry
; 29(38): e202300477, 2023 Jul 06.
Article
em En
| MEDLINE
| ID: mdl-37038277
ABSTRACT
A new class of conjugated macrocycle, the cyclo[4]thiophene[4]furan hexyl ester (C4TE4FE), is reported. This cycle consists of alternating α-linked thiophene-3-ester and furan-3-ester repeat units, and was prepared in a single step using Suzuki-Miyaura cross-coupling of a 2-(thiophen-2-yl)furan monomer. The ester side groups help promote a syn conformation of the heterocycles, which enables formation of the macrocycle. Cyclic voltammetry studies revealed that C4TE4FE could undergo multiple oxidations, so treatment with SbCl5 resulted in formation of the [C4TE4FE]2+ dication. Computational work, paired with 1 Hâ
NMR spectroscopy of the dication, revealed that the cycle becomes globally aromatic upon 2e- oxidation, as the annulene pathway along the outer ring becomes Hückel aromatic. The change in ring current for the cycle upon oxidation was clear from 1 Hâ
NMR spectroscopy, as the protons of the thiophene and furan rings shifted downfield by nearly 6â
ppm. This work highlights the potential of sequence control in furan-based macrocycles to tune electronic properties.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tiofenos
/
Furanos
Idioma:
En
Revista:
Chemistry
Assunto da revista:
QUIMICA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
ALEMANHA
/
ALEMANIA
/
DE
/
DEUSTCHLAND
/
GERMANY