a protecting group such as removal of a benzyl group by hydrogenolysis utilizing palladium on carbon in a suitable solvent system such as an alcohol acetic acid and the like or mixtures thereof a t butoxy based group including t butoxy carbonyl protecting groups can be removed utilizing an inorganic or organic acid such as hcl or trifluoroacetic acid in a suitable solvent system such as water dioxane and or methylene chloride another exemplary protecting group suitable for protecting amino and hydroxyl functions amino is trityl other conventional protecting groups are known and suitable protecting groups can be selected by those of skill in the art in consultation with greene and wuts protective groups in organic synthesis 3rd ed john wiley amp sons new york 1999 when an amine is deprotected the resulting salt can readily be neutralized to yield the free amine similarly when an acid moiety such as a phosphonic acid moiety is unveiled the compound may be isolated as the acid compound or as a salt thereof particular examples of the presently disclosed compounds include one or more asymmetric centers thus these compounds can exist in different stereoisomeric forms accordingly compounds and compositions may be provided as individual pure enantiomers or as stereoisomeric mixtures including racemic mixtures in certain embodiments the compounds disclosed herein are synthesized in or are purified to be in substantially enantiopure form such as in a 90 enantiomeric.