General Papers ARKIVOC 2014 (iv) 204-214 Page 204 © ARKAT-USA, Inc An efficient synthesis of tetrahydropyrazolopyridine derivatives by a one-pot tandem multi-component reaction in a green media Minoo Dabiri, a* Peyman Salehi, b* Majid Koohshari, a Zoleikha Hajizadeh, a and David Ian MaGee c* a Department of Chemistry, Faculty of Science, Shahid Beheshti University, G. C., Evin, Tehran 1983963113, Iran b Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 1983963113, Iran c Department of Chemistry, 30 Dineen Drive University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 E-mail: m-dabiri@sbu.ac.ir, p-salehi@sbu.ac.ir, dmagee@unb.ca DOI: http://dx.doi.org/10.3998/ark.5550190.0015.400 Abstract The synthesis of some tetrahydropyrazolopyridine derivatives has been described by a one-pot 2A + 2B + C + D four component reaction of a 1,3-dicarbonyl compound, an aldehyde, hydrazine and ammonium acetate in ethanol as a green media under catalyst-free condition. Keywords: 1,4-Dihydropyridine, dipyrazolopyridine, multi-component reactions, green chemistry Introduction Green chemistry is a doctrine that inspires chemists to design chemical procedures that minimize the use and production of hazardous materials. In fact, the goal of green chemistry is to reduce and prohibit the pollution of nature and ensure perpetual life on the earth. 1-3 Multi-component reactions (MCRs) require the combination of at least three compounds to generate a product, where all or most of the starting material atoms exist in the final product. 4 The use of MCRs for the synthesis of complex molecules in one pot, is advantageous compared to the classical routes that uses sequential synthesis. Owing to their usefulness for synthesizing drug-like molecules and creating high structural diversity, MCRs play an important role in combinatorial chemistry and industrial chemistry. 5,6 Simple purification, atom economy, convergent character, operational simplicity, elimination of overflow steps are other typical advantages of these reactions. 7 Since the first example of MCRs reported by Strecker, multi-component reactions have been developed regularly and many useful MCRs such as Mannich, Passerini (three-component