Esters prodrugs that cross the blood brain barrier can be ideal drugs for treatment of diseases of the central nervous system because the cerebral spinal fluid contains an abundance of esterases. The prodrug can be hydrolyzed into an active drug and a metabolite such as cholesterol that is known to be non-toxic and is familiar to the central nervous system. This invention describes a modification of the Fischer-Speier or Fischer esterification reaction in which one reagent is lipophilic and the other reagent is hydrophilic. The reaction occurs in a heterogeneous mixture. The preferred catalyst is 1.0 M hydrochloric acid and the preferred solvent is acetone. The presence of ester synthesis was confirmed by the hydroxamic acid-ferric perchlorate reaction. The synthesis can be conducted without chemical scaffolds and without protecting functional groups.
