On water catalyst-free synthesis of benzo[d]imidazo[2,1-b] thiazoles and novel N-alkylated 2-aminobenzo[d]oxazoles under microwave irradiation

Abstract

A highly efficient unprecedented catalyst-free microwave-assisted procedure for synthesizing benzo[d]imidazo[2,1-b]thiazoles and N-alkylated 2-aminobenzo[d]oxazol in green media was developed.

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

“…The substituent in the imidazole ring is of principal importance for antiviral activity because it was shown that the replacement of the aryl group by a smaller thiophene substituent drastically increases the antiviral action. Catalyst-free MW-assisted method for preparation of annulated heterocyclic structures in aqueous medium was demonstrated by the synthesis of benzo[d]imidazo[2,1-b]thiazoles 44a-l (Scheme 36) [65]. As a polar protic "green" co-solvent capable of easy absorbing MW-radiation, isopropanol was used.…”

“…The highest antitumor effect was observed for compounds having electron-donor 6-substituents in the benzothiazole fragment and electron-acceptor substituents in the aniline phenyl ring. Catalyst-free MW-assisted method for preparation of annulated heterocyclic structures in aqueous medium was demonstrated by the synthesis of benzo[d]imidazo[2,1-b]thiazoles 44a-l (Scheme 36) [65]. As a polar protic "green" co-solvent capable of easy absorbing MWradiation, isopropanol was used.…”

“…As a rule, condensed heterocyclic systems possess various types of biological activity. Catalyst-free MW-assisted method for preparation of annulated heterocyclic structures in aqueous medium was demonstrated by the synthesis of benzo[d]imidazo[2,1-b]thiazoles 44a-l (Scheme 36) [65]. As a polar protic "green" co-solvent capable of easy absorbing MW-radiation, isopropanol was used.…”

[CMMIM][BF4–] Ionic Liquid-Catalyzed Facile, One-Pot Synthesis of Chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-ones: Evaluation of Their Photophysical Properties and Theoretical Calculations

“…Given that they take into account both the diversity and convolution in organic synthesis, one-pot multi-component reactions are becoming more popular. Perks of the MCR include cost-effectiveness, ease of the process, a low E -factor, good atom economy, and complex product formation with a limited number of synthesis steps. , Also, one-pot synthesis and usage of environmentally benign reaction media are highly desired as they conserve time, limit chemical waste generation, and make practical aspects simpler like purification. , Several MCRs have previously been investigated by our research group. − …”

A Facile Microwave-Assisted Synthesis of Oxazoles and Diastereoselective Oxazolines Using Aryl-Aldehydes, p-Toluenesulfonylmethyl Isocyanide under Controlled Basic Conditions

“…In the last decade, the combined application of microwave-assisted irradiation in green solvents has increased considerably owing to the generation of quick products in the nontoxic environment. In this respect, isopropanol is a very attractive nontoxic green polar solvent for several competent organic reactions that could solubilize numerous reactants at room or high temperatures. − Herein, we developed an expedient microwave-assisted simple protocol of 5-substituted oxazoles and diastereoselective 4,5-disubstituted oxazolines derivatives using K 3 PO 4 as a base in an IPA reaction medium …”