First Total Synthesis of Inaoside A

The first total synthesis of inaoside A, an α‐D‐ribofuranoside isolated by our group from the edible mushroom Laetiporus cremeiporus, is described. The key reaction was an α‐selective Schmidt glycosylation. Most reported syntheses of ribofuranosides following the general Schmidt glycosylation procedure preferentially give β‐ribofuranosides. In contrast, using a 2,3,5‐tri‐O‐(tert‐butyldimethylsilyl)‐protected ribofuranoside substrate, which is easy to prepare and can be deprotected after glycosylation, revealed that the α‐ribofuranoside was preferentially obtained.