Highly efficient synthesis and application of aryl diazonium salts via femtosecond laser-tailored 3D flow microfluidic chips

The first example of the microfluidic chips (MFCs) consisting of centimeter-level 3D channels with high-density and large-volume fabricated by femtosecond laser micromachining were utilized to develop a time-saving, economical and hazardless flow synthesis process, and its advantages have been proved by in situ formation of aryldiazonium salts and subsequent borylation with bis(pinacolato)diboron. There are several important advantages in our 3D MFC-based flow synthesis technology, including the following: (1) the reaction temperature was altered from ice bath to room temperature; (2) the residence time was reduced by 10 times; (3) the yield was greatly improved, that is, several arylboronates were successfully obtained with higher yield compared to traditional batch process. Therefore, it can be envisioned that a novel, simplified flow synthetic protocol will be developed toward green organic synthesis via MFCs.