Palladium on carbon-catalyzed synthesis of 2- and 2,3-substituted indoles under heterogeneous conditions.
A mild, efficient and LiCl-free synthetic method for indole derivatives based on the heteroannulation of alkynes with 2-iodoanilines was achieved using palladium on carbon (Pd/C) and NaOAc in heated NMP. The N-tosyl protection of 2-iodoaniline expedited the reaction progress, while other protecting groups, such as tert-butoxycarbonyl, acetyl, and benzyloxycarbonyl groups, underwent deprotection under the present conditions. A variety of di- and monosubstituted alkynes could effectively react with N-tosyl-2-iodoaniline to give the corresponding indoles in good to high yields.
Laboratory of Organic Chemistry, Department of Organic and Medicinal Chemistry, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan.
Yasunari
Y
Monguchi
Shigeki
S
Mori
Satoka
S
Aoyagi
Azusa
A
Tsutsui
Tomohiro
T
Maegawa
Hironao
H
Sajiki
D000480:Alkynes / Q000737:chemistry; D000814:Aniline Compounds / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D018021:Lithium Chloride / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*
D000480:Alkynes; D000814:Aniline Compounds; D007211:Indoles; D010165:Palladium; D002244:Carbon; D018021:Lithium Chloride; C023650:aniline