4,4′-Trimethylenedipiperidine, a safe and greener alternative for piperidine, catalyzed the synthesis of N-methyl imines

A practical and facile synthesis of various N-methyl imines, versatile scaffolds, was conducted at 85 degrees C using 4,4 '-trimethylenedipiperidine as a safe and green catalyst. This reagent is a commercially available solid and can be handled easily. It has high thermal stability, low toxicity, and good solubility in green solvents such as water and ethanol. The regenerated catalyst demonstrated stable activity after several recycle runs, and any changes were detected in its chemical structure by H-1 NMR monitoring. The novelty of the current work is that the 4,4 '-trimethylenedipiperidine can act as a promising alternative for piperidine in organic reaction at higher temperatures due to its broad liquid range temperature, thermal stability, acceptor/donor hydrogen bond property, and other unique merits. Furthermore, the current protocol avoids waste generation in the workup process, which is a drawback in most previous reported procedures.