Indium Trichloride (InCl₃) Catalyzed Synthesis of Fused 7‐Azaindole Derivatives Using Domino Knoevenagel‐Michael Reaction

Abstract

An efficient and high yielding methodology developed for the synthesis of fused 7‐azaindole derivatives via one pot multicomponent assembly process of cyclic 1,3‐dicarbonyls with substituted aldehydes and 5‐amino‐1‐tert‐butyl‐1H‐pyrrole‐3‐carbonitrile. The transformation occurs via domino Knoevenagel‐ Michael reaction followed by intramolecular cyclization in the presence of catalytic amount of InCl3 (10 mol %). Mild reaction conditions, easy isolation of products, and good to excellent yields in a shorter period of time are the silent features of present methodology. Structures of all the newly prepared compounds have been corroborated by various spectroscopic methods.

A Decade of Indium‐Catalyzed Multicomponent Reactions (MCRs)

“…In the second approach, the tetracyclic 7-azaindole derivatives are obtained in one-step in excellent yields. [36] The same indium salt was employed in the multicomponent synthesis of highly functionalized pyranopyrazoles (13 examples), in a high-atom economic and sustainable synthetic process. The final products were obtained in excellent yields through the reaction of different aromatic aldehydes, phenyl-pyrazolone, and nitroketene-N,S-acetal (Scheme 11C).…”

“…In the first case, the MCR leads to the formation of dihydro‐7‐azaindoles in excellent yields, which can be further aromatized in the presence of the oxidant 4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile (DDQ) in almost quantitative yields. In the second approach, the tetracyclic 7‐azaindole derivatives are obtained in one‐step in excellent yields . The same indium salt was employed in the multicomponent synthesis of highly functionalized pyranopyrazoles (13 examples), in a high‐atom economic and sustainable synthetic process.…”

Synthesis and structural features of indium(iii) furan-2-thiocarboxylates showing efficient catalytic activity toward multicomponent reactions via Knoevenagel condensation

“…[9][10][11] In recent years, several scientific articles describing the significance of indium(III) salts along with indium metal-organic frameworks (MOFs) and organoindium compounds in homoand heterogeneous catalysis [12][13][14] have been published. Indium (III) based catalysts have been explored on several multicomponent reactions such as classical Ugi reaction, 15,16 epoxide-based Passerini reaction, 17 multiple isocyanide insertion reactions, 18 A 3 -coupling reaction, 19 Knoevenagel-initiated MCR, [20][21][22][23][24][25][26] and Hantzsch-type dihydropyridine and pyrrole synthesis, 27 and multi-catalytic systems and nanocatalysts for the synthesis of poly-substituted heterocycles, 28,29 quinoline derivatives and amino carbazole derivatives. [30][31][32][33][34][35][36][37] However, the In(III) complexes with S/O donor ligandcatalyzed MCRs are scanty.…”