Regioselective hydrolysis of myo-inositol 1,3,5-orthobenzoate via a 1,2-bridged 2 '-phenyl-1 ',3 '-dioxolan-2 '-ylium ion provides a rapid route to the anticancer agent Ins(1,3,4,5,6)P-5

Acid hydrolysis of myo-inositol 1,3,5-orthobenzoate leads regioselectively to 2-O-benzoyl-myo-inositol via a 1,2-bridged 2'-phenyl-1',3'-dioxolan-2'-ylium ion observed by H-1 and C-13 NMR spectroscopy, providing the precursor for a highly efficient route to the anticancer agent myo-inositol 1,3,4,5,-6pentakisphosphate.