Herein, we describe the generation of different highly reactive monoalkyl and phenyl ketenes using a dehalogenation procedure under flow conditions. All ketenes could be generated in good yields (determined by quenching with an appropriate aniline derivative) and showed high reactivity in the [2+2] cycloaddition with different imines, resulting in the formation of a range of β-lactams at room temperature in less then 10 mins. Furthermore, initial experiments were performed using these reactive ketenes for the synthesis of β-lactams under flow conditions.