Graphene Oxide as a Heterogeneous Reagent Promoted Synthesis of 2-Substituted 1,3-Benzazoles in Water

Abstract

An efficient chemical method for the synthesis of benzimidazoles, benzothiazoles, and benzoxazoles has been developed through the condensation of various aldehydes with o-phenylenediamine, o-aminothiophenol, and o-aminophenol using graphene oxide (GO) as an oxidant in water. These benzazoles are also prepared through a one-pot oxidation/condensation tandem process by reacting alcohols with 2-amino(thio)phenol/aniline in the presence of GO in poly(ethylene glycol) as a safe media. Moreover, this carbonaceous material could be readily separated using a simple filtration.

Minor Impact of Ligand Shell Steric Profile on Colloidal Nanocarbon Catalysis

“…Carbon surfaces are known to be populated with surface quinone moieties, 22,23 and quinone--based molecular catalysts are known to mediate the aerobic oxidation of primary amines with excellent selectivity. 34,35 Similar reactivity has also been reported for graphene oxide catalysts, 36 leading us to postulate that graphitic carbon colloids could also mediate this conversion. In-deed, as--received Monarch 1300 catalyzes the aerobic oxi-dation of benzylamine with selective formation of N-benzyl--1--phenylmethanimine (Scheme 2 and Figure S4).…”

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe3O4 hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

“…Owing to the interesting properties of their derivatives, functionalization of benzothiazoles to give 2‐substituted benzothiazoles have attracted much attention in recent years. The conventional methods for synthesis of 2‐substituted benzothiazoles includes using metals as catalysts for intramolecular cyclization reactions and also the condensation of 2‐aminothiophenol with alcohols, aldehydes, ketones, carboxylic acids, halides, ammonium triflates, β‐oxodithioesters and amines . However, having harsh and hazardous reaction conditions, use of expensive reagents and metal catalysts or strong acidic or oxidative conditions, and also tedious workup procedures for separation of the pure products are the disadvantages for most of these transformations .…”

From methylarenes to esters: efficient oxidative Csp3–H activation promoted by CuO decorated magnetic reduced graphene oxide

“…Graphene oxide (GO) was obtained according to the modified Hummers’ method in which the oxidation of natural flake graphite (particle size: <50 μm; from Merck) was performed using a mixture of H 2 SO 4 /KMnO 4 . 29 The ultrasonication of the produced graphite oxide (0.1 mg mL −1 ) in water for 1 hour resulted in the suspension of GO sheets.…”