Synthesis and Template Studies of New Aza Macrocycles and one Cryptand Based on 2,6-diaminopyridine and its Computational NMR Studies Using Density Functional Theory

Abstract

New ten macrocycles 5a-cand e-k and one cryptand 5d were synthesized by the reaction of diamine compounds 4a-k with N,N'-bis(2-chloroacetamido)-2,6-diaminopyridine (BCDP) 3 in the presence of K2CO3 and KI in good to high yields. Also the template effects of cations such as Na+, K+, K+/KI and Cs+ on the reaction yields for macrocycles (4a-c and I, k) were investigated. In this study it is found that size matching and template effect of K+ with KI as catalyst are most suitable for macrocyclization process. The structures of macrocycles and cryptand were confirmed by IR, 1H NMR, 13C NMR and Mass spectroscopies. Additionally, computational 1H and 13C NMR parameters of cryptand 5d were obtained using density functional theory (DFT) at B3LYP/6-31G* level. The calculated chemical shifts were found to be in agreement with experimental data. Keywords: Aza macrocycle, cryptand, 2, 6-Diaminopyridine, template effect, computational NMR.