μ-Waves avoid large excesses of diisobutylaluminium-hydride (DIBAL-H) in the debenzylation of perbenzylated α-cyclodextrin

Regioselective double deprotection of cyclodextrins using diisobutylaluminium-hydride (DIBAL-H) has become an important tool in functional cyclodextrin synthesis. When conventionally heated a very large excess of reagent is necessary for the reaction to happen, when μ-waves irradiation is employed the quantity of DIBAL-H can be lowered down to 5 equiv. Reaction with a smaller quantity of DIBAL-H never achieved complete double debenzylation. These results also sustain the mechanistic hypothesis according to which a minimum of two aluminium atoms are necessary for each debenzylation to occur.