Generation of Diversity Sets with High sp3 Fraction Using the Photoredox Coupling of Organotrifluoroborates and Organosilicates with Heteroaryl/Aryl Bromides in Continuous Flow.

The photoredox cross-coupling of aryl halides and potassium alkyl trifluoroborates is a very effective means to form Csp3-Csp2 bonds. However, this transformation is inefficient for the coupling of unactivated primary trifluoroborates. We have developed a generally useful, continuous flow Csp3-Csp2 coupling procedure for the synthesis of diverse product sets that is compatible with both trifluoroborates and silicate reagents. This universal protocol provides diversity sets from both primary and secondary coupling partners. This easily scalable procedure widens the substrate scope of the coupling reaction and is efficient for producing a greater range of analogues bearing a high sp3 fraction.