Acylation of methyl pipecolinate (I) with methyl oxalyl chloride (II) provides oxamate (III). Subsequent addition of 1,1-dimethylpropylmagnesium chloride (IV) to oxamate (III) gives rise to keto amide (V). The methyl ester group of (V) is then hydrolyzed by means of LiOH, yielding the intermediate carboxylic acid (VI)
3,3-Diphenyl-1-propanol (VII) is converted into the corresponding alkyl bromide (VIII) by treatment with CBr4 and PPh3. Reaction of bromide (VIII) with thiourea provides the isothiouronium salt (IX), which is further hydrolyzed to thiol (X) under alkaline conditions. Finally, acylation of thiol (X) with carboxylic acid (VI) by means of DCC yields the target thioester