Nanostructured Na\({}_{2}\)CaP\({}_{2}\)O\({}_{7}\): A New and Efficient Catalyst for One-Pot Synthesis of 2-Amino-3-Cyanopyridine Derivatives and Evaluation of Their Antibacterial Activity  
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1 Laboratory of Organic Synthesis, Extraction, and Valorization, FSAC, Hassan II University of Casablanca, B.P. 2693 Maarif, Casablanca 2000, Morocco; [EMAIL_ADDRESS] (R.A.); [EMAIL_ADDRESS] (A.T.); [EMAIL_ADDRESS] (M.D.); [EMAIL_ADDRESS] ([EMAIL_ADDRESS] (A.I.); [EMAIL_ADDRESS] ([EMAIL_ADDRESS] (A.I.); [EMAIL_ADDRESS] ([EMAIL_ADDRESS] ([EMAIL_ADDRESS] (A.I.); [EMAIL_ADDRESS] ([PERSON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]RSON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]RSON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ERSON]ON]ON]ON]ON]ON]RSON]ON]ON]ON]RSON]ON]ON]RSON]RSON]ON]ON]ON]RSON]RSON]RSON]ON]RSON]RSON]RSON]ON]ON]RSON]ON]ON]ON]ON]ON]RSON]ON]ON]ON]ON]ON]ON]ON]RSON]ON]RSON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ON]ERSON]ON]ERSON]ERSON]ERSON][PERSON]ERSON]ON]E.j.  
involving the \(\beta\)-enaminonitrile moiety represent a class of intermediates considered to be extremely reactive and used as precursors for synthesis of brand-new heterocyclic compounds [9; 10; 11]. The literature mentions that several different pyridine derivatives, particularly 2-amino-2-cyanopyridines, have been prepared as target structures using sustainable catalyst materials [12] coupled with environmentally benign protocols. Moreover, it is interesting to note that multicomponent reactions (MCRs) have drawn the attention of many researchers in the last decade due to their productivity and simplicity. MCRs are used for the development of biologically active compounds from accessible commercial reagents with a single step [13]. Furthermore, in our case, the combination of this process with a solvent-free medium for the preparation of these heterocyclic derivatives makes the use of MCRs compliant with the principles of green chemistry.  
Several studies have reported the usefulness and importance of these processes, in which they were exploited for the synthesis of 2-amino-3-cyanopyridine in the presence of various catalysts, such as ytterbium perfluoroctanoate [Yb(PFO)3] [14], Bu4N\({}^{+}\)Br\({}^{-}\)[15], Cu@imineZCMNPs [16], cellulose-SO3H [17], MgO [18], HBF4 [19], Fe3O4@SiO2@(CH2)lm] C(CN)3 [20], FePO4 [21], and poly(ethylene glycol) (PEG-400) [22]. However, these procedures present several inconveniences, such as long reaction time, undesirable reaction conditions, the need for loads of reagents, the use of organic solvents and toxic reagents, and the non-recoverability of the catalyst. Thus, a new, efficient, and environmentally friendly protocol for the synthesis of 2-amino-3-cyanopyridines is required. The aim of this work is to investigate and examine Na2 CaP2O7 as an alternative catalyst, as it has received increased attention recently, mainly in the environmental field [23; 24; 25].  
This work is a continuation of our investigation and according to our results obtained in a previous study based on adopting Na2 CaP2O7 as a catalyst in organic synthesis [26; 27; 28], particularly in the synthesis of heterocyclic compounds via multicomponent reactions in an ecofriendly medium [29; 30]. Herein, we report here an efficient and rapid one-pot synthesis of thirteen 2-amino-3-cyanopyridine derivatives by condensation of aromatic aldehydes, malonomitrile, methyl ketone, or cyclohexanone and ammonium acetate using a nanostructured diphosphate Na2 CaP2O7 as a heterogeneous catalyst under solvent-free reaction conditions at 80 \({}^{\circ}\)C (Scheme 1). Five prepared 2-amino-3-cyanopyridine were converted to pyrido[2,3-\(d\)]pyrimidines, and we examined the antibacterial activity of all prepared compounds.