Introduction of a New Ionic Liquid Based on Tropine for the Acceleration of the Synthesis of Several Hetero-Aromatic Compounds and Investigation of Its Physicochemical Property and Antibacterial Activity

In this work, we synthesized a new ionic liquid ([C۸-Tropine].Cl) by combining tropine with ۱-chlorooctane without the use of any solvent. Prepared ionic liquid was characterized utilizing Mass, TGA, CHN, FESEM, NMR, and FT-IR analysis techniques. Potential energy surfaces of different pathways and calculated energy barriers beside a few NMR chemical shifts were explored to determine the structure of the catalyst. According to the Curtin-Hammett principle, two different products can be obtained, named Min۲a and Min۲b, in a ratio of ۰.۲۶:۱ which the structures of these products were determined by comparing the experimental and calculated NMR chemical shifts. The calculations were performed using the DFT (B۳LYP) computational method with ۶-۳۱+G(d,p) and ۶-۳۱۱G(d,p) basis sets. The antibacterial activity of the catalyst was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) using the agar well diffusion method. After the identification of the synthesized ionic liquid, it was utilized as an efficient catalyst for the synthesis of pyrido[۲,۳-d]pyrimidines, ۱,۲,۴-triazolo[۴,۳-a]pyrimidines, bis-۲-amino-۴H-pyrane and spiro-۲-amino-۴H-pyran-oxyindole derivatives. These methods stand out for their convenient and uncomplicated catalyst preparation, minimal catalyst usage, straightforward work-up procedures, quick reaction times, and the ability to achieve good to high product yields under environmentally friendly conditions. Furthermore, the catalyst can be easily recovered and reused several times.

Keywords:

Bis-۲-amino-۴H-pyrane , Ionic Liquids , Pyrido [۲ , ۳-d]pyrimidines , Solvent-free , Spiro-۲-amino-۴H-yran-oxyindole ۱ , ۲ , ۴-Triazolo[۴ , ۳-a]pyrimidines , Tropine