Polyethylene glycol-promoted synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives in water

ABSTRACT Synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives were achieved using polyethylene glycol (PEG-400) as promoting reaction medium in water under catalyst-free conditions at reflux and room temperature, respectively. The structure of pyrimido[1,2-a]benzimidazole was confirmed using 1H NMR, 13C NMR, DEPT, and HMBC experiments. The promising points for the present methodology are efficiency, generality, high yield, short reaction time, cleaner reaction profile, ease of product isolation, simplicity, potential of recycling reaction medium, and finally agreement with green chemistry protocols. GRAPHICAL ABSTRACT

[1]  H. Chavan,et al.  Polyethylene glycol in water: Simple, efficient, and catalyst-free synthesis of 4H-pyran derivatives , 2016 .

[2]  M. Pal,et al.  FeF3-catalyzed MCR in PEG-400: ultrasound assisted synthesis of N-substituted 2-aminopyridines , 2016 .

[3]  K. Ramesh,et al.  A novel one pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives using recyclable PEG-400 , 2015 .

[4]  Eelco Ruijter,et al.  Multicomponent reactions: advanced tools for sustainable organic synthesis , 2014 .

[5]  M. A. El‐Remaily.  Synthesis of pyranopyrazoles using magnetic Fe3O4 nanoparticles as efficient and reusable catalyst , 2014 .

[6]  Y. Jeong,et al.  p-Toluenesulfonic acid-catalyzed one-pot synthesis of 2-amino-4-substituted-1,4-dihydrobenzo[4,5]imidazolo[1,2-a]pyrimidine-3-carbonitriles under neat conditions , 2014 .

[7]  Hong-Xia Liu,et al.  Meglumine promoted one-pot, four-component synthesis of pyranopyrazole derivatives , 2013 .

[8]  Mostafa A. Hussein,et al.  Design, synthesis and molecular docking of some new 1,2,4-triazolobenzimidazol-3-yl acetohydrazide derivatives with anti-inflammatory-analgesic activities , 2013, Archives of pharmacal research.

[9]  Yanlong Gu.  Multicomponent reactions in unconventional solvents: state of the art , 2012 .

[10]  A. Corma,et al.  Homogeneous and heterogeneous catalysts for multicomponent reactions , 2012 .

[11]  V. Vyas,et al.  Substituted benzimidazole derivatives as angiotensin II-AT1 receptor antagonist: a review. , 2010, Mini reviews in medicinal chemistry.

[12]  P. Roy,et al.  Solvent free synthesis, anti-inflammatory and anticancer activity evaluation of tricyclic and tetracyclic benzimidazole derivatives. , 2010, Bioorganic & medicinal chemistry letters.

[13]  M. Shaaban,et al.  Synthesis and analgesic/anti-inflammatory evaluation of fused heterocyclic ring systems incorporating phenylsulfonyl moiety. , 2008, Bioorganic & medicinal chemistry.

[14]  A. Spasov,et al.  Benzimidazole derivatives: Spectrum of pharmacological activity and toxicological properties (a review) , 2006, Pharmaceutical Chemistry Journal.

[15]  Mohit L. Deb,et al.  Uncatalysed Knoevenagel condensation in aqueous medium at room temperature , 2005 .

[16]  Robin D. Rogers,et al.  Polyethylene glycol and solutions of polyethylene glycol as green reaction media , 2005 .

[17]  Ashutosh Kumar Singh,et al.  Anti-inflammatory, analgesic and antiamoebic activity evaluation of pyrimido[1,6-a]benzimidazole derivatives synthesized by the reaction of ketoisothiocyanates with mono and diamines. , 2002, European journal of medicinal chemistry.

[18]  R. Houghten,et al.  The Current Status of Heterocyclic Combinatorial Libraries. , 1997, Chemical reviews.

[19]  H. Weissbach,et al.  Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5, 6-dimethylbenzimidazole. , 1960, The Journal of biological chemistry.

[20]  J. B. Wright.  The chemistry of the benzimidazoles. , 1951, Chemical reviews.