## 2 Results and Discussion  
First, the behavior of chalcone **1** toward aminopyrazole derivative **2a**, which may serve as a precursor to bioactive pyrazolo[1,5-a]pyrimidine derivatives, was scrutinized utilizing the Q-Tube system. Initially, a group of solid basic catalysts were tested for the mentioned aza Michael addition reaction (Scheme 1). The solid basic catalysts used in the reaction depicted in Scheme 1 are named potassium carbonate, basic alumina, KF-Basic alumina, and Mg-Al-Hydrotalcite (Mg-Al-HT) (Table 1). These choices are based on a high degree of reusability and low environmental impact. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Entry**} & \multirow{2}{*}{**Catalyst**} & \multicolumn{2}{c}{**(Reflux) *} & \multicolumn{2}{c}{**MW **} & \multicolumn{2}{c}{**Q-Tube **} \\ \cline{3-8}  & & **Yield** & **Time** & **Yield** & **Time** & **Yield** & **Time** \\ \hline
1 & None & 0 & 12 h & 0 & 50 min & 0 & 50 min \\
2 & K\({}_{2}\)CO\({}_{3}\) & 58\% & 12 h & 75\% & 40 min & 75\% & 40 min \\
3 & Basic alumina & 61\% & 9 h & 84\% & 30 min & 82\% & 35 min \\
4 & KF/basic & & & & & & \\ alumina & & & & & & \\
5 & Mg-Al HT & 77\% & 6 h & 96\% & 12 min & 95\% & 10 min \\ \hline \hline \end{tabular}  
* Equimolar amounts of reactants in ethanol at 70 \({}^{\circ}\)C, **Equimolar amounts of reactants at 100 \({}^{\circ}\)C.  
\end{table} 
Table 1: Optimization of the reaction condition for the synthesis of fused pyrimidines. Table 1 shows that when utilizing the Q-tube system, the excellent yield and shortest reaction time was attained via Mg Al-HT (95%, 10 min. entry 5). Also, KF-basic alumina and basic alumina itself provided good results (entry 3 and entry 4), but the lowest yield were attained with potassium carbonate (entry 2). In all cases, only one isolable product was obtained, as examined by TLC. To address the beneficiary effect of the Q-tube system on the above-mentioned reaction, all the above experiments (Table 1) were compared with conventional heating and microwave irradiation (Table 1). Both the Q-tube system and microwave reactor exerted pressure on the reaction, and their results were almost similar, though the Q-tube is still the best because it is economical and easier than the microwave reactor. Also, Table 1 proves that the Q-tube system reduced the reaction time from 6 h under conventional conditions to 10 min and increased the reaction yield from 77% yield under conventional conditions to 95% yield. The superiority of Mg Al-HT as a solid basic catalyst is in line with our previous results for the aza-Michael addition reaction [16]. An explanation for the outstanding effect of the Q-tube is based on the fact that chemical reactions are forced via the acceleration of transitions between liquids, solids, and gases. Pressure effects can be explained by the effect on reaction volume and activation volume [26]. A high-pressure chemistry process can improve the physical properties of solvents, reagents, and final products, achieving cleaner and faster transformations. The physical properties of liquids are the most modified. When pressure is increased, vapor pressure directly correlates with solvent boiling points [27; 28; 29]. According to the Arrhenius equation, the reaction rate can double with every 10 \({}^{\circ}\)C increase in temperature [30]. Scheme 1 shows the formation of aza-Michael addition adducts that could be converted into a product and formulated as **3a**, **4a**, or its isomer **5a**. The \({}^{1}\)H and \({}^{13}\)C NMR spectra of products obtained from the reaction proved the presence of a (-CH\({}_{2}\)-CH-) building block and ruled out an NH function that is consistent with structures for **3a** or its isomer **5a**.