Arcadi A,
Cacchi S,
*,
Marinelli F.
Università degli Studi “La Sapienza”, Rome, Italy
A Versatile Approach to 2,3-Disubstituted Indoles through the Palladium-Catalyzed
Cyclisation of
o-Alkynyltrifluoro-acetanilides with Vinyl Triflates and Aryl Halides.
Tetrahedron Lett. 1992;
33: 3915-3918
DOI:
10.1016/s0040-4039(00)74818-0
Key words
palladium catalysis - indole synthesis - anilines
Significance
Indoles are structural motifs found in a wide variety of natural products and pharmaceutical
agents. While other palladium-catalyzed indole syntheses had been primarily focused
on the cyclization of compounds containing pre-installed substituents of the desired
indole, Cacchi and co-workers demonstrated a modular synthesis of 2,3-disubstituted
indoles using a variety of 2-alkynyl anilines and aryl halides or vinyl triflates,
streamlining the synthesis of this class of compound.
Comment
The authors note that other bases such as triethylamine performed poorly compared
to potassium carbonate. Similarly, indole products were not observed when employing
aniline derivatives with a free amino group or acetamido group, highlighting the importance
for a stronger electron-withdrawing group to be present on the nitrogen atom.
