Enabling Construction of Boron-Stereogenic Formyl BODIPYs via <i>N</i>-Heterocyclic Carbene-Catalyzed Enantioselective Esterification

Boron-stereogenic formyl boron dipyrromethene dyes (BODIPYs) have shown notable potential as chiral fluorescent sensors to recognize amino acid enantiomers owing to their remarkable photophysical properties. However, the catalytic asymmetric synthesis of boron-stereogenic formyl BODIPYs remains challenging due to the lack of efficient strategies. Herein, we report an organocatalytic approach by utilizing <i>N</i>-heterocyclic carbene (NHC) catalysis to achieve enantioselective esterification, enabling the construction of boron-stereogenic formyl BODIPYs in moderate to good yields with excellent stereoselectivity. The formyl group in these boron-stereogenic BODIPYs serves as a multifunctional handle, facilitating diverse postsynthetic modifications and endowing them with promising applications in chiral recognition. Importantly, the achieved enantiopure BODIPYs exhibit moderate photophysical properties in circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. Furthermore, the enantioselective fluorescent recognition of cysteine and diaminocyclohexane enantiomers by using <i>R</i>-<b>3aa</b> reveals their great potential as chiral probes. This study not only offers a practical and environmentally friendly approach to access boron-stereogenic BODIPYs but also underscores their potential applications as chiral fluorescent sensors.