Carboxylic Acid Catalyzed Three-Component Aza-Friedel−Crafts Reactions in Water for the Synthesis of 3-Substituted Indoles

Abstract

[reaction: see text] The carboxylic acid catalyzed three-component aza-Friedel-Crafts reactions of aldehydes, primary amines, and indoles in water have been developed. The aza-Friedel-Crafts products could be easily transformed to various 3-substituted indoles including biologically active compounds. This system offers a novel efficient method for the synthesis of 3-substituted indoles.

A novel pyrrolidinium ionic liquid with 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoroethoxy)ethanesulfonate anion as a recyclable reaction medium and efficient catalyst for Friedel–Crafts alkylations of indoles with nitroalkenes

“…Brønsted acids are usually used as catalysts for Friedel-Crafts alkylation [30][31][32][33][34]. Friedel-Crafts reaction of indoles with nitroalkenes was always catalyzed by Brønsted acids and Lewis acids [34][35][36][37].…”

Bis[( l )prolinate-N,O]Zn: A water-soluble and recycle catalyst for various organic transformations

“…Since water has specific properties [107], [108], [109], [110], [111], [112], [113], [114] a disadvantage comes with the insolubility of organic compounds [115], [116], [117]. A novel, greener approach was adopted for the synthesis [118] of dicoumarols ( 88 ) using bis[( l )prolinate-N,O]Zn as a mild, non-toxic, Lewis acid catalyst in water employing 4-hydroxycoumarin ( 86 ) and aromatic/heteroaromatic aldehydes ( 87 ) (Scheme 20).…”

Discovery of the First Irreversible Small Molecule Inhibitors of the Interaction between the Vitamin D Receptor and Coactivators

“…Then indole (2 mmol) and decanoic acid (0.2 mmol, 10 mol%) 32 were added slowly as a solution in toluene (2 ml). The reaction mixture was stirred at room temperature and monitored by TLC.…”