The first total syntheses of 1-O-[(phosphonooxy)hydroxyphosphinyl]-2,3,4,5,6-pentakis-O-phosphono-D- myo-inositol (10) and its antipode (11) were achieved from enantiopure 2,3:5,6-di-O-cyclohexylidene-D-myo-inositol (6). The critical pyrophosphate function was introduced, in the presence of flanking phosphate triesters, by mild LiCN-mediated cleavage of a mixed phosphate methyl ester, isolation of the resultant lithium salt, and addition to dibenzyl chlorophosphonate. The benzyl esters were removed by catalytic hydrogenolysis over Pd in t-BuOH/H2O in the presence of NaHCO3. Comparisons of synthetic and enzyme-devived pyrophosphates with two phosphatases suggests natural material has the stereochemical configuration in 10.