NHC-Catalyzed Regioselective Desymmetrizing Esterification Enables Access to Planar Chiral Ferrocenyl Saccharides

Planar chiral ferrocene-saccharide conjugates integrate multiple stereogenic elements and exhibit distinctive physicochemical and biological properties, rendering them highly attractive as chiral auxiliaries and diagnostic probes. However, their structural complexity─especially the intricate chirality and the requisite ester linkage─poses considerable synthetic challenges. Herein, we report an efficient N-heterocyclic carbene (NHC)-catalyzed strategy for the regioselective installation of prochiral ferrocene dicarboxaldehydes onto specific hydroxyl (OH) groups of unprotected saccharides. The synergistic combination of specific chiral NHC catalysts and boronic acids allows for simultaneous regioselectivity amplification and desymmetrization, affording ferrocene-saccharide conjugates with high regiocontrol and excellent planar chirality. This protocol operates under mild conditions and accommodates a broad range of ferrocene and saccharide substrates, thereby significantly expanding the accessible chemical space of planar-chiral ferrocene hybrids.