New protocols for the synthesis of 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4] triazolo [1,5-a] pyrimidine-6-carboxylate esters using an efficient additive

Authors : Nader GHAFFARİ KHALİGH, Taraneh MİHANKHAH, Salam TİTİNCHİ, Zohreh SHAHNAVAZ, Mohd RAFİE JOHAN

Pages : 1100-1109

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :This work introduces a new additive named 4,4’-trimethylenedipiperidine for the practical and ecofriendly preparation of ethyl 5-amino-7-insert ignore into journalissuearticles values(4-phenyl);-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate derivatives. This chemical is commercially available and easy to handle. It also possesses a low melting point and a broad liquid range temperature, high thermal stability, and good solubility in water. Based on green chemistry principles, the reaction was performed in a); a mixture of green solvents i.e. water and ethanol insert ignore into journalissuearticles values(1:1 v/v); at reflux temperature, and b); the additive was liquefied at 65 ◦ C and the reaction was conducted in the liquid state of the additive. High yields of the desired triazolo-pyrimidines were obtained under both aforementioned conditions. Our results demonstrated that this additive, containing 2 Lewis base sites and able to act as an acceptor-donor hydrogen bonding group, is a novel and efficient alternative to piperidine, owing to its unique properties such as its reduced toxicity, nonflammable nature, nonvolatile state, broad liquid range temperature, high thermal stability, and ability to be safely handled. Furthermore, this additive could be completely recovered and exhibited high recyclability without any change in its chemical structure and no significant reduction in its activity. The current methodology has several advantages: insert ignore into journalissuearticles values(a); it avoids the use of hazardous materials, as well as toxic, volatile, and flammable solvents, insert ignore into journalissuearticles values(b); it does not entail tedious processes, harsh conditions, and the multistep preparation of catalysts, insert ignore into journalissuearticles values(c); it uses a metal-free and noncorrosive catalyst, and insert ignore into journalissuearticles values(d); reduces the generation of hazardous waste and simple work-up processes. The most important result of this study is that 4,4’-trimethylenedipiperidine can be a promising alternative for toxic, volatile, and flammable base reagents in organic synthesis owing to its unique properties.
Keywords : Organic catalysis, Lewis base, heterocycles, three component reactions, sustainable chemistry