Practical synthesis of photochromic diarylethenes in integrated flow microreactor systems

An effective method for the synthesis of photochromic diarylethenes through the generation of heteroaryllithiums and subsequent reaction with octafluorocyclopentene has been developed by using integrated flow microreactor systems. Reactions can be conducted without using cryogenic conditions by virtue of effective temperature and residence time control, although much lower temperatures (<-78 °C) are needed for batch macroreactions. Moreover, the synthesis of unsymmetrical diarylethenes, which is difficult to achieve when using conventional batch macrosystems, has been accomplished based on the selective introduction of one aryl group to give arylheptafluorocyclopentene followed by the introduction of another aryl group. The productivity of the laboratory-scale system is approximately 0.5 mmol min(-1). Therefore, the present integrated flow microreactor method serves as a practical way of synthesizing various photochromic diarylethene derivatives.