Light-Driven Routes to Strained Borylated Rings

Light-Driven Routes to Strained Borylated Rings

Author: ChemistryViews

Huan-Ming Huang and colleagues, ShanghaiTech University, China, have demonstrated two visible-light-driven methods to construct borylated strained ring systems, key motifs in drug and materials development. The team uses energy transfer catalysis to enable a rare type of photorearrangement involving boron.

In the first method, the researchers designed a substrate featuring a carbon–boron σ-bond and a nearby carbon–carbon π-bond, separated by a single sp³ carbon. Under visible light and energy transfer catalysis, this arrangement undergoes what they term a “π, σ-methane rearrangement.” Activation generates a diradical species, triggering a 1,4-boron shift and smoothly forming borylated cyclopropanes.

When a weak C–H bond is present, energy transfer similarly yields a diradical, but this time it undergoes 1,5-hydrogen atom transfer (HAT) followed by cyclization, leading to borylated cyclobutanes.

 


HBpin =  pinacolborane

Together, these two complementary pathways show how the combination of suitable visible-light energy transfer catalysis and substrate design can efficiently generate structurally complex, borylated strained rings under mild conditions. The catalytic platform permits a broad substrate scope and good functional group toleration. According to the researchers, this provides chemists with powerful new tools for building boron-rich frameworks.