Flash chemistry: flow microreactor synthesis based on high-resolution reaction time control.

This article addresses a fascinating aspect of flash chemistry, high-resolution reaction-time control by virtue of a flow microreactor system, and its applications. The length of time that the solution remains inside the reactor is called the residence time. The residence time between the addition of a reagent and that of a quenching agent or the next reagent in a flow microreactor is the reaction time, and the reaction time can be greatly reduced by adjusting the length of a reaction channel in a flow microreactor. This feature is quite effective for conducting reactions involving short-lived reactive intermediates. A reactive species can be generated and transferred to another location to be used in the next reaction before it decomposes by adjusting the residence time in the millisecond to second timescale. The principle of such high-resolution reaction-time control, which can be achieved only by flow microreactors, and its applications to synthetic reactions including Swern-Moffatt-type oxidation, as well as the generation and reactions of aryllithium compounds bearing electrophilic substituents, such as alkoxycarbonyl groups, are presented. Integration of such reactions using integrated flow microreactor systems is also demonstrated.