1914-00-7Relevant academic research and scientific papers
Palladium-catalysed dehydrogenative generation of imines from amines. A nature-inspired route to indoles via cross-couplings of amines with arylhydrazines
Taddei, Maurizio,Mura, Manuel G.,Rajam?ki, Suvi,De Luca, Lidia,Porcheddu, Andrea
, p. 3002 - 3013 (2014/03/21)
H-substituted imines are elusive compounds formed when aldehydes or ketones are mixed with ammonia. However, this class of molecules can be prepared through selective removal of a hydrogen molecule from a primary amine using a transition metal catalyst. This biomimetic transformation, previously employed for the N-alkylation of anilines, is applied here to a domino preparation of differently substituted indoles from aliphatic primary amines and arylhydrazines. Several different linear and branched aliphatic primary amines are oxidized with reusable palladium on charcoal to the corresponding primary imines entrapped as arylhydrazones that can be isolated as such. Arylhydrazones can be further converted into N-alkylindole derivatives via an acid-mediated indolisation reaction. The one-pot domino hydrogen transfer Fischer indole synthesis under heterogeneous catalysis is also possible, giving access to diverse substituted indoles, including NH indoles obtained after deprotection of the corresponding benzyl compounds. The truly heterogeneous nature of the catalyst was demonstrated by recycling the catalyst in the same reaction, and in other palladium-catalysed transformations.
Palladium-catalyzed indole, pyrrole, and furan arylation by aryl chlorides
Nadres, Enrico T.,Lazareva, Anna,Daugulis, Olafs
supporting information; experimental part, p. 471 - 483 (2011/04/15)
The palladium-catalyzed direct arylation of indoles, pyrroles, and furans by aryl chlorides has been demonstrated. The method employs a palladium acetate catalyst, 2-(dicyclohexylphosphino)-biphenyl ligand, and an inorganic base. Electron-rich and electron-poor aryl chlorides as well as chloropyridine coupling partners can be used, and arylated heterocycles are obtained in moderate to good yields. Optimization of base, ligand, and solvent is required for achieving best results.
INDOLE SYNTHESES UTILIZING o-METHYLPHENYL ISOCYANIDES.
Ito,Kobayashi,Seko,Saegusa
, p. 73 - 84 (2007/10/02)
New indole synthesis starting with o-methylphenyl isocyanides such as o-tolyl, 2,4-xylyl, and 2,6-xylyl isocyanide is described. Treatment of o-tolyl isocyanide with LDA in diglyme at minus 78 degree C generated selectively o-(lithiomethyl)phenyl isocyanide in an almost quantitative yield, which on warming up to room temperature was cyclized to indole after aqueous workup. Similarly, 2,4-xylyl and 2,6-xylyl and 2,6-xylyl isocyanides were cyclized to 5-methylindole and 7-methylindole quantitatively. The o-(lithiomethyl)phenyl isocyanides reacted with electrophiles such as alkyl halides and alkylene oxides to give o-alkylphenyl isocyanides, which were cyclized via the lithiation at the orthobenzylic carbon to afford 3-substituted indoles.
INDOLE DERIVATIVES. 121. CONVENIENT METHOD FOR THE PREPARATION OF N-ALKYLINDOLES
Suvorov, N. N.,Plutitskii, D. N.,Smushkevich, Yu. I.
, p. 268 - 270 (2007/10/02)
A new method was developed for the synthesis of N-alkylindoles from phenylhydrazones of aldehydes and ketones that makes it possible to obtain diverse N-alkylindoles under mild conditions.
A NEW MODIFICATION OF THE FISCHER REACTION. SYNTHESIS OF N-ALKYLINDOLES UNDER THE CONDITIONS OF EXTRACTIVE BASE CATALYSIS
Suvorov, N. N.,Plutitskii, D. N.,Smushkevich, Yu. I.
, p. 766 - 769 (2007/10/02)
A new modification of the Fischer reaction, which makes it possible to obtain 1-alkyl-, 1-alkyl-2-aryl, 1,3-dialkyl-, and 1,2,3-trialkylindoles under the conditions of interphase base catalysis, was developed.
