Facile preparation of two tetrols from permethylated α-cyclodextrin and unambiguous NMR analysis

An unprecedented straightforward approach wherein an excess of diisobutylaluminum hydride is able to strip off in reasonable yield (45%) and in a regioselective manner four methyl groups from permethylated α-cyclodextrin, to provide a symmetric tetrol (2) in one chemical step from a commercially available material is described. An asymmetric tetrol (3) was also isolated from the reaction as a minor product (19%). Both compounds are unambiguously characterized by 1H NMR, 13C NMR, COSY, HSQC and HRMS.