Abstract
Allylation of phenols, a widely used reaction in multistep synthetic pathways, was herein investigated using mechanochemistry. This synthesis was first optimized on vanillin by varying key parameters including both chemical (e.g., stoichiometry, reaction time, liquid additive) and mechanical (e.g., rotational speed, material, size and number of beads) conditions, leading to the isolation of allylated vanillin at the gram scale in excellent yield (95%). The optimized procedure was also successfully implemented to another bio-based phenol of interest, ethyl ferulate (92% isolated yield). The environmental impact of these procedures was compared with more classical in-solution protocols by calculating E factors, clearly indicating the superiority of the ball-milling approach over the solution-based procedures. Thus, the present work demonstrates that mechanochemistry is a versatile, efficient and waste-less method for the allylation of biobased phenols such as vanillin and ethyl ferulate.