Synthesis of 1‐Amino‐1H‐indole‐3‐carboxylates by Copper(I)‐Catalyzed Intramolecular Amination of Aryl Bromides

Abstract

A simple route to various N‐substituted 1‐amino‐1H‐indole‐3‐carboxylates by use of copper(I)‐catalyzed intramolecular N‐arylation has been established. For the preparation of N‐monosubstituted and N‐unsubstituted derivatives, the cyclization of Boc‐protected enehydrazines and subsequent deprotection were applied. Furthermore, 1‐alkoxyindole‐3‐carboxylates can be synthesized by use of the same protocol(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Transition Metal‐Catalyzed Synthesis of Fused Five‐Membered Aromatic Heterocycles

“…A variety of primary alkyl-and aryl-amines, including sterically hindered ones, can be employed in this reaction, affording indole products 233 in good to high yields. More recently, the same group extended this approach to a facile Cu(I)-catalyzed assembly of pharmacologically important 1-amino-and 1-hydroxyindoles [152] 235 from easily available enehydrazines 234 (Scheme 9.83) [236]. In the case of benzylsubstituted substrates, arylation reaction was accompanied by an oxidation process leading to the formation of N-benzyledene-1-aminoindole-3-carboxylates.…”

Ferric chloride-catalyzed synthesis of indoles using the intramolecular amination of aryl bromides

“…The parameters of the 1 H NMR, 13 C NMR, and mass spectra for the sample obtained of indole 1c were identical to the data reported by Melkonyan et al [17].…”

“…Methyl Ester of 1-Dimethylaminoindole-3-carboxylic Acid (1c) was obtained analogously in 77% yield from enamine 2c [17] as a brown oil. The parameters of the 1 H NMR, 13 C NMR, and mass spectra for the sample obtained of indole 1c were identical to the data reported by Melkonyan et al [17].…”

“…In light of the advantages of using iron catalysts, we undertook a study of the feasibility of replacing copper catalysts in a synthetic strategy, which we previously employed for the preparation of N-substituted methyl esters of indole-3-carboxylic acids [16] and methyl esters of 1-aminoindole-3-carboxylic acids [17], with a catalyst containing ferric salts. We initially carried out the synthesis of indole 1a from the corresponding enamine 2a using the cyclization condition proposed in previous work [16], replacing CuI by FeCl 3 .…”

Synthesis of N‐Substituted Condensed Tetrahydropyridine‐Based Enaminones via Palladium‐Catalyzed Intramolecular C–N Cross‐coupling

“…Within them, the C–N cross‐coupling variant (Buchwald–Hartwig reaction) is probably the most widespread carbon‐heteroatom bond‐forming reaction, and protocols allowing successful N ‐arylations of practically all imaginable substrates can be found in the literature . Compared with other substrates, enaminones and related compounds are still rather neglected substrates from this point of view . Owing to the lowered nucleophilicity of their nitrogen atom, enaminones can be challenging substrates for this kind of transformation.…”