Base-promoted aerobic oxidative synthesis of fused 1,3,5-triazines under metal-free conditions

Abstract

An efficient base-promoted aerobic oxidation procedure for the synthesis of fused 1,3,5-triazines from 2-aminobenzimidazoles, aromatic aldehydes and ammonium iodide has been developed. In this multi-component protocol, ammonium iodide served as...

Base‐Promoted Three‐Component Cyclization and Coupling Strategy for the Synthesis of Substituted 3‐Aryl‐5‐thio‐1,3,4‐thiadiazole‐2‐thiones

“…First, reaction of 1 a with 3 under base conditions provides intermediate 7, which is further reacted with another one molecule of 3 to produce intermediate 8 and a proton. [28] Then, the intramolecular condensation of intermediate 8 delivers intermediate 9, which is converted into intermediate 6, accompanied with the release of H 2 S. The extrusion of H 2 S was confirmed by Pb(OAc) 2 test papers (see Figure S2).…”

Transition‐Metal‐Free Synthesis of N‐Heterocyclic Compounds via Multi‐Component Reactions

“…Chen and colleagues reported the metal-free one-pot synthesis of benzimidazole-fused 1,3,5-triazines 631 via a MCR of basepromoted aerobic oxidative coupling of 2-aminobenzimidazoles 630, aromatic aldehydes 1 and ammonium iodide (Scheme 129). [147] The reaction was carried out in presence of NaHCO 3 in DMSO and NH 4 I serves as one of the nitrogen sources for the construction of four new C À N bonds in the desired product 631. The overall reaction involves the generation of an imine intermediate through a condensation reaction of benzaldehyde 1, 2-aminobenzimidazole 630 and ammonium iodide which then cyclizes and undergoes oxidative dehydrogenation reaction to afford the desired product 631 with moderate to good yields.…”

“…Chen and colleagues reported the metal‐free one‐pot synthesis of benzimidazole‐fused 1,3,5‐triazines 631 via a MCR of base‐promoted aerobic oxidative coupling of 2‐aminobenzimidazoles 630 , aromatic aldehydes 1 and ammonium iodide (Scheme 129). [147] …”

Base-promoted fused β-carboline formation from 2-(1H-indol-3-yl)cyclohexan-1-ones, aldehydes and ammonium salts

“…In this context, using ammonium salts as a nitrogen source, simple and effective approaches for constructing structurally diverse N-heterocycles have been reported. 12 In recent years, our group also successfully utilized ammonium salts as a nitrogen source for a facile construction of thiazoles, 13 quinazolines, 14 pyridines, 15 pyrimidines, 16 pyrroles, 17 benzimidazo[1,2- a ]-1,3,5-triazine, 18 phenothiazines, 19 and heteroaromatic-fused indoles. 20 In continuation of our interest in utilizing ammonium salts to synthesize N-heterocycles under metal-free conditions, herein we report a novel strategy for the formation of β-carbolines from 2-(indol-3-yl)cyclohexanones, aldehydes, and ammonium salts (Fig.…”