Loperamide oxide (CAS NO.: 106900-12-3), with its systematic name of trans-4-(p-Chlorophenyl)-4-hydroxy-N,N-dimethyl-alpha,alpha-diphenyl-1-piperidinebutyramide 1-oxide, could be produced through many synthetic methods.

Following is one of the synthesis routes:

Firstly, 2-Oxo-3,3-diphenyl-tetrahydrofuran (I) is treated with HBr(g) to produce bromo derivative (II), and the yielding compound is the converted into butyryl chloride derivative (III) in the presence of thionyl chloride with refluxing chloroform. Next, derivative (III) reacts with dimethylamine (IV) in toluene to give dimethyl (tetrahydro-3,3-diphenyl-2-furylidene)ammonium bromide (V), which is then condensed with 4-(4-chlorophenyl)-4-piperidinol (VI) in the presence of Na₂CO₃ and KI in refluxing 4-methyl-2-pentanone to provide N,N-dimethyl butyramide derivative (VII). Finally, the target product is obtained by N-oxidation of the piperidine ring in (VII) by heating with H₂O₂ in MeOH/methylbenzene or in 4-methyl-2-pentanone.