Processes for making bicyclic compounds and precursors thereof, and particularly for making [1.1.1]propellane and bicyclo[1.1.1]pentane and derivatives thereof, utilize continuous flow reaction methods and conditions. A continuous process for making [1.1.1]propellane can be conducted under reaction conditions that advantageously minimize clogging of a continuous flow reactor. A continuous flow process can be used to make precursors of [1.1.1]propellane.