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[reaction: see text] The synthesis of the pyrazino[1,2-a]indole nucleus was achieved by intramolecular cyclization of several 2-carbonyl-1-propargylindoles in the presence of ammonia. The reaction conditions were optimized using microwave heating and a pool of catalysts. Cyclization of 1-alkynylindole-2-carbaldehydes was easily accomplished under standard(More)
Silver and gold salts and complexes mainly act as soft and carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I)/Au(III)-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their(More)
Two unprecedented oxygenated aaptaminoids have been synthesized starting from cheap and easily available 2,3-dihydroxybenzoic acid with the satisfactory overall yields of 31% and 34%. The key step of the procedure is the divergent thermic 5-exodig vs base-promoted 6-endodig cyclization of a 5-alkynylquinolinone derivative.
A new gold-catalyzed reaction of ynamides with 3-substituted indoles as nucleophiles is reported. The reaction allows for the synthesis of a new class of 2-vinylindole derivatives in good yields via the intermediacy of a cyclopropyl gold-carbenoid species.
A Lewis acid-catalysed diastereoselective [4 + 2] cycloaddition of vinylindoles and methyl 2-acetamidoacrylate, leading to methyl 3-acetamido-1,2,3,4-tetrahydrocarbazole-3-carboxylate derivatives, is described. Treatment of the obtained cycloadducts under hydrolytic conditions results in the preparation of a small library of compounds bearing the free amino(More)
A study on the SN2-type ring opening reactions of aziridines with indoles as nucleophiles is reported. Under gold(i) catalysis a great variety of tryptamine derivatives were prepared in good to excellent yields with complete stereocontrol when chiral aziridines were used. We demonstrated that cationic gold(i) catalysts are superior Lewis acids to the(More)
Indole 2-carboxamide derivatives 4 underwent palladium-catalyzed intramolecular cyclization reactions to afford beta-carbolinones or pyrazino[1,2-a]indoles according to different reaction pathways. The complete regioselectivity of the reactions was obtained in different reaction conditions.
A small library of six polarity-sensitive fluorescent dyes, nicknamed MediaChrom, was prepared. This class of dyes is characterized by a pyrimidoindolone core fitted out with a conjugated push-pull system and a carboxy linker for a conceivable coupling with biomolecules. The optimized eight-step synthetic strategy involves a highly chemo- and regioselective(More)
A general one-pot synthesis of pyridines 4a-t from the reaction of dialkyl acyclic/cyclic ketones 1a-i, methyl, aryl/heteroaryl ketones 1m-r, and aldehydes bearing alpha-hydrogens 1s,t with propargylamine 2 is described. Gold and copper salts are efficient catalysts for the reaction of ketones with 2. The formation of the pyridines 4 is suggested to proceed(More)
[reaction: see text] An original TiCl(4)/t-BuNH(2)-mediated hydroamination/annulation domino reaction of delta-keto-acetylenes is described. The synthesis of pyrrolo[1,2-a]indole-2-carbaldehydes, starting from 2-carbonyl-1-propargyl-1H-indoles runs under mild reaction conditions. A conceivable mechanism is also discussed. TiCl(4) has proved to be an(More)