Abstract
The reaction between ketene animal/ketene N,S-acetals (derived from diamines/cysteamine hydrochloride and 1,1-bis(methylthio)-2-nitroethene) with aromatic aldehydes, and Meldrum's acid led to the title compounds. The reaction conditions were optimized using response surface methodology (RSM). The two independent variables (temperature and water content of aqueous ethanol), and the responses (yield of product and reaction time) were studied. The range of each parameter selected was: T = 25–100 °C and water = 0–100%. The optimal values were: T = 72 °C and water = 33%. This work offers significant advantages including use of a green solvent, experimental simplicity, absence of catalyst, a simple work-up and purification process, moderate to good yields, and preparation of potentially bioactive compounds.
Highlights
Response surface methodology (RSM) is the most popular optimization method used in recent years
In 2017 and 2018 we developed an efficient, one-pot, multi-component synthesis of imidazopyridine, pyridopyrimidine, thiazolopyridine, and oxazolopyridine fused heterocyclic systems via reaction of various diamines, cysteamine hydrochloride, ethanolamine, 1,1-bis(methylthio)-2-nitroethene, cyanoacetohydrazide and aromatic aldehydes in ethanol at re ux
We have reported a simple and clean synthesis of imidazopyridinone, pyridopyrimidinone, and thiazolopyridinone derivatives
Summary
Response surface methodology (RSM) is the most popular optimization method used in recent years. RSM is a powerful mathematical and statistical technique which has been widely used for designing experiments and empirical building models with minimal experimental number This method is exclusively used to examine the surface, or the relationship between the response and the factors affecting the response. Optimum conditions with respect to yield, purity of product and reaction time were as follow: temperature 72 C, water content of aqueous ethanol 33%. On the basis of the central composite design, the cubic model relationship between the experimental yield (R1) and the process variables (temperature (A) and water content of aqueous ethanol (B)) in coded units is obtained from eqn (1). Thiazolopyridinone derivatives through a simple one-pot, multicomponent reaction of diverse diamines or cysteamine hydrochloride, 1,1-bis(methylthio)-2-nitroethene, aromatic aldehydes, and 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid) in ethanol/water (2 : 1) at 72 C (Scheme 1, Entry d). RSM in conjunction with a central composite design was used for modeling and optimizing the synthetic process
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