Recent Progress in the Boron-Mediated Aglycon Delivery: Reaction Development, Synthesis of Useful Glycosides, and Its Application to Chemical Biology

There are many glycosides with 1,2-cis-O-glycosidic linkages (1,2-cis glycosides) in biologically active natural products and drugs. The development of new lead compounds for drugs by elucidating the mechanisms of their biological activities and developing their structures has attracted attention. However, the stereoselective synthesis of 1,2-cis-glycosides is still a challenging task due to the lack of general methods corresponding to the neighboring group participation method for the 1,2-trans-stereoselective glycosylation. In this context, we have developed organoboron-catalyzed regio- and 1,2-cis-stereoselective glycosylation method, namely, boron-mediated aglycon delivery (BMAD). This review article describes the recent progress in the BMAD method since our review article published in this journal in 2020, including (1) diastereoselective desymmetric BMAD reaction of meso-diols, (2) BMAD reaction of trans-1,2-diols using a diboron catalyst, (3) total synthesis of terpioside B using BMAD reaction, (4) β-arabinofuranosylation using BMAD reaction, and (5) chemical-biological studies using late-stage BMAD reaction.