An efficient and environmentally sustainable domino protocol for the synthesis of structurally diverse spiroannulated pyrimidophenazines using erbium doped TiO₂ nanoparticles as a recyclable and reusable heterogeneous acid catalyst

Abstract

An efficient and environmentally sustainable domino protocol has been presented for the synthesis of structurally diverse spiroannulated pyrimidophenazines involving a four component reaction of 2hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, cyclic ketones and amino derivatives in the presence of erbium doped TiO 2 nanoparticles as a recyclable and reusable heterogeneous acid catalyst.The present synthetic protocol features mild reaction conditions with operational simplicity, excellent yield with high purity, short reaction time and high atom economy with the use of a recoverable and reusable environmentally sustainable heterogeneous catalyst.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

“…2% Er-doped TiO 2 NP-catalyzed Michael addition-cyclization for the synthesis of spiroannulated pyrimidophenazines (333a/b/c) was reported by Kumar et al (Scheme 230) in ethanol under reux using 2-hydroxynaphthalene-1,4-dione (191), ophenylene diamine (33e), aminopyridines derivatives (110n) and cyclic ketones (285i/294c/235). 409 The Zr-dependent porous coordination polymer ligated with amino-terephthaline (Zr-PCP-NH 2 )-catalyzed ultrasoundmediated synthesis of 2-phenyl benzimidazoles (83h), and 1,2disubstituted benzimidazoles (85k) was reported recently by Mahmoudi et al via the cyclocondensation of o-phenylene diamines with aryl carbaldehydes (21a) (Scheme 231). 410 The yields of 83h and 85k were found to be higher under ultrasonic conditions rather that high speed stirring conditions.…”

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

“…The synthesis of these hybrid molecules with advantageous heterocyclic substructures involves the four-component reaction of 2-hydroxynaphthalene-1,4-dione 105, benzene-1,2-diamine 171, cyclic ketones (163, 173 and 148) and 2-aminoazines 172 in the presence of erbium-doped TiO 2 NPs as a recyclable and reusable heterogeneous acid catalyst under refluxing ethanol ( Scheme 54 ). 123 The doping of TiO 2 with erbium was found to enhance the catalytic efficiency of TiO 2 , facilitating the reaction to provide the products with comparatively better yields.…”

Guanine‐La complex supported onto SBA‐15: A novel efficient heterogeneous mesoporous nanocatalyst for one‐pot, multi‐component Tandem Knoevenagel condensation–Michael addition–cyclization Reactions

“…Benzo [a] pyrano [2, 3‐c] phenazine and 4,4′‐(arylmethylene)‐bis‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ols) compounds have a great potential in order to be applied in biological and pharmaceutical systems such as antifungal, anticancer, antiplasmodial, antimalarial, antibacterial, antiparasitic, anticancer and antichagasagen systems . However, synthesis of these useful compounds needs a better method which should be in agreement with green chemistry rules.…”