Continuous Flow Synthesis of β‐Aminoketones as Masked Vinyl Ketone Equivalents

Herein we report the efficient synthesis of β‐aminoketones via addition of a vinyl Grignard reagent into amides followed by trapping of the vinyl ketone intermediate with the magnesium‐amide by‐product. The reaction was successfully translated from a batch process into continuous flow mode to increase its efficiency, safety and scalability. Different set‐ups were evaluated to minimize/overcome clogging issues arising from magnesium salt precipitates. Ultimately, the resulting β‐aminoketones were obtained in high yields and productivities with residence times of less than 90 seconds at elevated temperatures of 50 °C. Importantly, the β‐aminoketone products are valuable building blocks that can be unmasked to reactive vinyl ketones via a Cope elimination process.