Sterically Directed Site‐ and Stereoselective <i>O</i>‐Glycosylation of <i>tert</i>‐Butyl Gentisate

Gentisic acid 5-O-glycosides are a large family of plant-derived natural products that show a wide spectrum of bioactivities. However, their chemical synthesis is highly challenging, due to the site-selectivity issue that is quite difficult to tackle. Previous synthetic routes are very rare and suffer from inefficiency arising from tedious protection and deprotection manipulations. Herein, we report a sterically directed site- and stereoselective O-glycosylation of tert-butyl gensitate. The large steric hindrance of tert-butyl group plays an extremely important role in delivering excellent site- and stereoselectivities. This glycosylation protocol, followed by convenient and mild deprotections, allows for easy access to natural and bioactive gentisic acid 5-O-glycosides.