Insights into cascade and sequential one-pot pathways for reductive amination of aldehydes paired with bio-derived levulinic acid to N-substituted pyrrolidones using molecular hydrogen

Abstract

This work aims to explore cascade and sequential one-pot synthesis pathways for N-substituted pyrrolidones from aryl aldehydes and bio-derived levulinic acid (LA) using molecular hydrogen and ammonia. This process has been catalyzed using the non-noble metal catalyst, Ni–montmorillonite (Ni–MMT) nanocomposite, which has been extensively characterized for this work. It was observed that the sequential one-pot pathway provided significantly higher yields for the desired product with great atom economy, in comparison to the cascade pathway. The sequential one-pot pathway was further tested on aryl and selected aliphatic aldehyde substrates with moderate to substantial yields (63–86%) for N-substituted pyrrolidones. This nanocomposite catalyst was also applied for a process involving substituted anilines with levulinic acid, while yielding their corresponding pyrrolidone products in excellent yields. The Ni–MMT nanocomposite exhibited decent catalytic performance and recyclability of up to 6 cycles.