One-pot synthesis of N-substituted 2-methyl-4,5,6,7-tetrahydroindole derivatives

Sulfamic acid promoted one-pot multicomponent reaction: a facile synthesis of 4-oxo-tetrahydroindoles under ball milling conditions

“…Because of these important applications of heterocyclic compounds, different synthetic methods were developed for their production. 4 a – d However, most the methods are metal catalysed 4 e and have several limitations such as harsh reaction conditions, employment of toxic and expensive metals as catalysts, longer reaction time, non-reusability of catalysts etc. 4 f , g The dimedone reacts with α -chloroacetaldehyde in sodium carbonate to produced 4-oxo tetrahydrofuran which reacts with ammonium hydroxide to gives 4-oxo tetrahydroindole in another route depicted in ( Scheme 1 ).…”

New and General Nitrogen Heterocycle Synthesis: Use of Heteropoly Acids as a Heterogeneous Recyclable Catalyst

“…[1] Different tetrahydroindoles are found in the structures of many biologically active compounds, such as antibiotics, antipsychotic agents, [2] and blood platelet aggregation inhibitors. [3] They can also be used as ligands for transition metals.…”

“…[4] Various multistep synthetic procedures have been described in the literature, including reduction of indoles [5] or annulation reactions. [1] Synthesis of the pyridine ring system and its derivatives [6] occupies an important place in the realm of natural and synthetic organic chemistry because of the therapeutic and pharmacological properties of these compounds. They have emerged as integral backbones of more than 7,000 existing drugs.…”