Stereoselective Synthesis of 2-Fluoro-1,3-Diols via Lithium Binaphtholate-Catalyzed Aldol-Tishchenko Reaction

Lithium binaphtholate, readily prepared from ( R)-3,3'-I₂-BINOL and lithium tert-butoxide, efficaciously catalyzed the enantioselective aldol-Tishchenko tandem reaction of α-fluoroketones with aldehydes, achieving the enantioselective synthesis of 2-fluoro-1,3-diols with three contiguous stereogenic centers. Kinetic studies revealed that the aldol reaction and the subsequent hemiacetal formation are in equilibrium under the reaction conditions and that the lithium binaphtholate catalyst selectively promotes hydride shift of one of the eight stereoisomers to produce 2-fluoro-1,3-diols containing a tetrasubstituted fluorinated carbon center.