DIHYDROXYLATION OF FUNCTIONALIZED COUMARIN DERIVATIVES

7-Acetoxy- and 7-tosyloxycoumarins were successfully dihydroxylated in RuCl 3 /NaIO 4 /CeCl 3 system to give the corresponding glycol derivatives in excellent yields. Tricyclic coumarin with tetrasubstituted olefin function also gave the desired diol in good yield. Introduction of electron-deficient protecting group to coumarin skeleton is critical for the successful dihydroxylation.