An Efficient Synthesis of Benzo[g]thiazolo[2,3‐b]quinazolin‐4‐ium and Benzo[g]benzo[4,5]thiazolo[2,3‐b]quinazolin‐14‐ium Hydroxides by a One‐pot, Three‐component Reaction under Green Conditions

Abstract

A new series of benzo[g]thiazolo[2,3‐b]quinazolin‐4‐ium and benzo[g]benzo[4,5]thiazolo[2,3‐b]quinazolin‐14‐ium hydroxide derivatives have been synthesized by the one‐pot, three‐component reaction of aryl glyoxal monohydrates, 2‐hydroxy‐1,4‐naphthoquinone, and 2‐aminothiazole or 2‐aminobenzothiazole in the presence of triethylamine and p‐toluenesulfonic acid as organocatalysts in H2O/acetone (2:1) at room temperature. This method offers mild reaction conditions, excellent yields, easy workup, and readily accessible starting materials and catalysts.

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives

“…By the use of different cyclic β-diketones, 2-aminobenzothiazoles and aromatic aldehydes, three series (12 examples) of structurally diverse spiroheterocycles have been synthesized in the aqueous medium in high yields (88-93%). A similar approach, but with p-TSA as a catalyst, was used to synthesize quinazoline derivatives of 2-aminobenzothiazole 41a-f [63]. The three-component reaction proceeds under mild conditions (aqueous acetone, room temperature) and includes a cascade of reactions (Scheme 33): Knoevenagel condensation reaction, Michael addition with subsequent intramolecular condensation of the imino group to the carbonyl group of the quinone fragment, and, finally, the intramolecular dehydration/aromatization of the intermediates and the keto-enol rearrangement.…”

Ultrasonic‐assisted preparation of Co3O4 and Eu‐doped Co3O4 nanocatalysts and their application for solvent‐free synthesis of 2‐amino‐4H‐benzochromenes under microwave irradiation

“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] One-pot, multicomponent reactions (MCRs) are widely used and an approved method due to their atom economy, high efficiency, and selective bond formations for synthesizing different types of heterocyclic compounds such as benzochromens, benzopyrans, and so many other materials with various applications. [27][28][29][30][31][32][33][34][35][36][37] Microwave irradiation is a novel and practical technique for reagent activation in synthesis of the organic compounds. This method has been applied successfully for the synthesis of heterocyclic compounds under moderate conditions, which have gained its popularity through the less reaction duration, modified products, environmental and commercial advantages, and simplified setup in comparison with conventional heating reactions.…”

“…One‐pot, multicomponent reactions (MCRs) are widely used and an approved method due to their atom economy, high efficiency, and selective bond formations for synthesizing different types of heterocyclic compounds such as benzochromens, benzopyrans, and so many other materials with various applications. [ 27–37 ]…”

One‐pot, three‐component synthesis of polyfunctionalized benzo[h]pyrazolo[3,4‐b][1,6]naphthyridine and benzo[g]pyrazolo[3,4‐b]quinoline derivatives in the presence of silver nanoparticles (AgNPs)

“…Aryl glyoxals are known as an important synthon in the preparation of complex hetero scaffolds due to the presence of two active sites that has made it as 1,2‐biacceptor which could be attacked by nucleophilic reagents. [ 18–21 ]…”