InBr3-promoted divergent approach to polysubstituted indoles and quinolines from 2-ethynylanilines: switch from an intramolecular cyclization to an intermolecular dimerization by a type of terminal substituent group.
Use of a 2-ethynylaniline having an alkyl or aryl group on the terminal alkyne selectively produced a variety of polyfunctionalized indole derivatives in moderate to excellent yields via indium-catalyzed intramolecular cyclization of the corresponding alkynylaniline. In contrast, employment of a substrate with a trimethylsilyl group or with no substituent group on the terminal triple bond, exclusively afforded polysubstituted quinoline derivatives in good yields via indium-promoted intermolecular dimerization of the ethynylaniline. This indium catalytic system successfully accommodated the intramolecular cyclization of other arylalkyne skeletons involving a carboxylic acid and an amide group.
Sakai
Norio
N
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan. sakachem@rs.noda.tus.ac.jp
Annaka
Kimiyoshi
K
Fujita
Akiko
A
Sato
Asuka
A
Konakahara
Takeo
T
D000114:Acetylene / Q000031:analogs & derivatives* / Q000737:chemistry; D000814:Aniline Compounds / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D019281:Dimerization; D007204:Indium / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry / Q000379:methods; D011804:Quinolines / Q000737:chemistry*
C483919:2-ethynylaniline; D000814:Aniline Compounds; D007211:Indoles; D011804:Quinolines; C530781:indium bromide; D007204:Indium; D000114:Acetylene