Synthesis of (+)-1,5-dideoxy-1,5-imino-d-galactitol, a potent α-d-galactosidase inhibitor

Galactose plays an important role in biological metabolism, vaccine preparation, glycoside synthesis, and so on. However, its low metabolic stability, poor binding affinity and other shortcomings limit its application. Introducing fluorine atom(s) into galactose has been used to improve its application performance. Deoxy-fluoro derivatives of galactose are not only vital substances for enzymes but also resourceful sugar benefactors for the synthesis of common products, and it shows great potential in vaccine preparation and enzyme inhibitor synthesis. The advancement of the scheme for the deoxy-fluorination of galactose has received considerable attention during the past decades. This review introduces a method of galactose modification to improve its application performance, and presents the recent development on the deoxy-fluorination of galactose at different sites using various fluorination reagents. Moreover, some good leaving groups used in deoxyfluorination process and some successful cases of galactose fluoridation on vaccine preparation and enzyme inhibitor synthesis are introduced simultaneously.