Rapid Synthesis of Fused Polycyclic Heteroaromatics through Successive Vinylic/Aromatic C−F Bond Activation

• Published in: European journal of organic chemistry 2022-10, Vol.2022 (37), p.n/a
• Main Authors: Fujita, Takeshi, Fukuda, Takuya, Suzuki, Naoto, Ichikawa, Junji
• Format: Article
• Language: English
• Subjects: Carbazoles; Coupling; Cyclization; Esters; Fluorine; Heterocycles; Indoles; Synthesis; Synthetic methods
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202200600

The synthesis of fused polycyclic heteroaromatics was achieved via successive vinylic/aromatic carbon−fluorine (C−F) bond activation. The Suzuki‐Miyaura coupling of (1‐bromo‐2,2‐difluorovinyl)biaryls with 2‐hydroxy‐ or 2‐aminophenylboronic acids (esters) followed by defluorinative 5‐endo‐trig cyclization yielded 2‐fluorobenzofurans (indoles) with a biaryl moiety in one‐pot operation. The obtained 2‐fluorobenzoheteroles underwent acid‐mediated intramolecular C−F/C−H coupling to yield tetra‐, penta‐, and hexacyclic heteroaromatics. This protocol allowed the synthesis of various substituted benzo‐fused dibenzofurans and carbazoles. The synthesis of fused polycyclic heteroaromatics was achieved via successive vinylic/aromatic C−F bond activation. The Suzuki‐Miyaura coupling of bromodifluoroalkenes with 2‐hydroxy‐ or 2‐aminophenylboronic acids (esters) followed by defluorinative 5‐endo‐trig cyclization afforded 2‐fluorobenzoheteroles bearing a biaryl moiety in one‐pot operation. Subsequent acid‐mediated intramolecular C−F/C−H coupling afforded tetra‐, penta‐, and hexacylic heteroaromatics.