DIBALH mediated reduction of the acetal moiety on perhydrofuro[2,3-b]pyran derivatives

The reaction of DIBALH with bis(heteroannulated)-pyranosides containing the perhydrofuro[2,3-b]pyran moiety is described. The hydride attack at the anomeric carbon (C-9a) resulted in the exclusive tetrahydrofuran ring opening. The selectivity of this reaction has been evaluated as other benzylidene acetals built on these substrates remain practically or partially unaltered in these conditions depending on the steric volume of the O-protecting group located at C-4 (TBDMS vs. Me). This protocol can be considered as a new entry for the synthesis of chiral and highly functionalized cyclopentanes.