Abstract
This work introduces a new additive named 4,4’-trimethylenedipiperidine for the practical and ecofriendly preparation of ethyl 5-amino-7-(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 (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: (a) it avoids the use of hazardous materials, as well as toxic, volatile, and flammable solvents, (b) it does not entail tedious processes, harsh conditions, and the multistep preparation of catalysts, (c) it uses a metal-free and noncorrosive catalyst, and (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.
Highlights
Solvents play a vital role in both academic and industrial research, and they can influence the reaction mechanism and route, selectivity, reaction rate, type, and yield of a product
Based on the unique properties of 4,4’-trimethylenedipiperidine (TMDP) and its successful catalytic applications in some organic synthesis [11,12,13], we were encouraged to investigate the potential of TMDP as a catalyst or dual solvent-catalyst for the preparation of 1,2,4-triazolo[1,5- a ]pyrimidines through a one-pot three-component reaction
Regarding the limited solubility of substrates in water, the experiments were conducted in a mixture solvent of water and ethanol (50:50% v/v), which lead to an improvement of the yield of 2a (Table 1, entry 5)
Summary
Solvents play a vital role in both academic and industrial research, and they can influence the reaction mechanism and route, selectivity, reaction rate, type, and yield of a product. The fabrication of some ionic liquids involves tedious procedures and harsh conditions, the use of toxic and corrosive reagents or expensive reactants, as well as toxic, flammable, and volatile solvents [2]. To overcome these issues, the design and development of sustainable solvents that are clean and involve green media is an attractive and promising area in organic chemistry. Based on the unique properties of 4,4’-trimethylenedipiperidine (TMDP) and its successful catalytic applications in some organic synthesis [11,12,13], we were encouraged to investigate the potential of TMDP as a catalyst or dual solvent-catalyst for the preparation of 1,2,4-triazolo[1,5- a ]pyrimidines through a one-pot three-component reaction
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
