Synthesis and reactions of ynolates via a stop-flow method with a flow microreactor

We report a method for the generation and subsequent reaction of ynolates in a flow microreactor via a stop-flow process. This procedure allowed for the synthesis of ynolates at ambient temperature within 11 min via a Li-Br exchange reaction with sec-butyllithium, whereas the corresponding batch process generally requires low temperature control and extended reaction times of up to 1 h. The stop-flow method is especially useful for optimizing the reaction time without having to use various microtube lengths. The resulting ynolates were applied to the olefination of carbonyl compounds and to pyrrole synthesis. These results indicate the practical utility of the ynolate reaction and should contribute to progress in flash chemistry.