Catalyst-free one-pot synthesis of isoindolin-1-imine derivatives via three-component reaction

Abstract

A novel, one-pot method has been developed for the synthesis of 4-(2-substituented-3-iminoisoindolin-1-ylidene)-1-substitueted-3-methyl-1H-pyrazol-5(4H)-one derivatives via cascade three-component condensation of 2-cyanobenzaldehyde, amine, and 3-methyl-1H-pyrazol-5(4H)-one or 1,3-dimethyl-1H-pyrazol-5(4H)-one. The efficient and convenient reaction conditions provide the corresponding products from various substrates under reflux condition in ethanol with excellent yields (85-95%).

Microwave-assisted synthesis of novel 8-chloro-[1,2,4]triazolo[4,3-$a$]pyridine derivatives

“…16 Generally, green chemistry has been attracting great interest from chemists because of its environmental benefits. 17 Many green methods, such as catalyst-free, 18 supercritical fluids, 19 ionic liquids, 20 solvent-free reactions, 21 and ultrasound 22 or microwave 23 irradiation as energy sources were applied in organic synthesis. Recently, microwave irradiation has become an effective tool in organic synthesis, because of its short reaction time and higher yields.…”

Multifaceted Behavior of 2‐Cyanobenzaldehyde and 2‐Acylbenzonitriles in the Synthesis of Isoindolinones, Phthalides and Related Heterocycles

“…A related one pot procedure was reported by the same authors in 2013 using, instead of the alcohols, 3‐methyl‐1H‐pyrazol‐5(4H)‐one, 1,3‐dimethyl‐1H‐pyrazol‐5(4H)‐one 146 or other active methylene compounds 148 (Scheme 59). [53,54] …”

“…A related one pot procedure was reported by the same authors in 2013 using, instead of the alcohols, 3-methyl-1Hpyrazol-5(4H)-one, 1,3-dimethyl-1H-pyrazol-5(4H)-one 146 or other active methylene compounds 148 (Scheme 59). [53,54] The synthesis of 1,3-diiminoisoindoline 152 was reported by Sato and co-workers in 1985 with reactions of N-(2cyanobenzylidene)aniline 150 obtained from 2-cyanobenzaldeyde, with elemental sulfur in liquid ammonia and amines in moderate yields and variable 151/152 ratios (Scheme 60). [55] A plausible pathway of this reaction was also proposed, involving two main steps: the oxidation of methine carbon with elemental sulfur in liquid ammonia giving thioamide A; the cyclization to B that seems to proceed by nucleophilic attack of a thiolate anion toward the nitrile carbon of A followed by substitution of the sulfur with ammonia as shown in the Scheme 61.…”