Flash flow chemistry is a subset of flow chemistry pioneered by Yoshida and Nagaki. The technique is suited to fast chemical processes in which reactive intermediates are generated. A flash flow synthesis utilises residence times on the order of seconds, meaning that slower side reactions can often be out-competed by a faster dominant and desired process, provided sufficient in-reactor mixing has been achieved. The flash flow approach has been most successfully applied to the generation of aryllithiums from aryl halides, followed by trapping with an electrophile (Scheme 1) and has facilitated the clean lithiation and trapping of aryl halides that are: liable to aryne formation, which bear esters, nitriles, and even ketones; feats which are difficult if not impossible to achieve using 'in flask' (batch) chemistry. In addition to aryllithium chemistry, flash flow chemistry may be successfully applied to chemistry involving carbenoids and saturated metalated heterocycles . A number of excellent reviews covering many of these aspects of flash flow chemistry in greater detail have been published .