steps wherein preferred reactants are shown to more clearly demonstrate the process of the invention r i is dimethyltridecyl in the following reaction scheme str10 as shown above step 1 involves the reduction of the amide compound ii to the amine using a borane complex such as borane with tetrahydrofuran thf dimethylsulfide diphenylsulfide dibenzylsulfide 1 4 oxathiane or bh 2 cl with dimethylsulfide or a metal boride such as zrcl 4 nabh 4 or ticl 4 nabh 4 in thf or other suitable solvent the reduction may also be carded out using titanium or zirconium borides or borane complexes with ammonia dimethylamine pyridine or piperazine preferred reduction agents include the borane complexes with tetrahydrofuran thf dimethylsulfide diphenylsulfide dibenzylsulfide 1 4 oxathiane or bh 2 cl with dimethylsulfide or a metal boride such as zrcl 4 nabh 4 or ticl 4 nabh 4 in thf or other suitable solvent any amide unconverted by this reduction is separated using reverse phase chromatography step ii involves the reaction of compound iii with thiophenol in acetonitrile and trifluoroacetic acid tfa to produce the phenylsulfide containing intermediate any moderate strength acid is expected to produce the intermediate in good yield other sulfides such as 4 methoxythiophenol 2 mercapto 1 methylimidazole and 2 mercaptobenzimidazole may be employed compound iii is extracted by application of the diluted reaction solution to a reverse phase c 18 column followed by elution with methanol the amount of tfa.