Cross-Coupling Reaction of Saccharide-Based Alkenyl Boronic Acids with Aryl Halides: The Synthesis of Bergenin

A convenient synthetic pathway enabling D-glucal and D-galactal pinacol boronates to be prepared in good isolated yields was achieved. Both pinacol boronates were tested in a series of cross-coupling reactions under Suzuki-Miyaura cross-coupling conditions to obtain the corresponding aryl, heteroaryl, and alkenyl derivatives in high isolated yields. This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandinD and the first total synthesis of bergenin.