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.