First Total Synthesis of Inaoside A

Abstract

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.