Catalytic enantioselective synthesis of boron-stereogenic BODIPYs

Boron dipyrromethenes (BODIPYs) are a class of tetracoordinate boron compounds that have attracted considerable interest in recent decades due to their excellent spectroscopic properties and structural versatility, leading to their widespread applications in chemical, biological, pharmaceutical and materials science. However, BODIPYs possessing boron-stereogenic centres in enantioenriched forms are rare and catalytic methodology to enantioselectively prepare a boron-stereogenic BODIPY remains elusive. Here we report a palladium-catalysed protocol for the enantioselective synthesis of boron-stereogenic BODIPYs via a desymmetric intramolecular C-H arylation reaction. This method gives access to a wide range of highly functionalized boron-stereogenic BODIPYs, including six- to nine-membered boron heterocycles, with good to excellent enantioselectivities. The discrimination of the two alpha C-H bonds of the BODIPY core is enabled by the co-action of steric hindrance and attractive interaction in the catalytic chiral pocket. Photophysical properties, derivatizations and applications in chiral recognition of the obtained chiroptical BODIPYs are investigated. This work enriches the chemical diversity of chiroptical BODIPY dyes. BODIPYs possessing boron-stereogenic centres are rare and it is challenging to develop catalytic methodologies to enantioselectively prepare these molecules. Now, a palladium-catalysed desymmetric intramolecular C-H arylation reaction for the enantioselective synthesis of boron-stereogenic BODIPYs is reported, which gives access to various six- to nine-membered chiral boron heterocycles with good enantioselectivity.