N-Benzyl 2-aminoethanethiol (I) is reacted with 1,1-bis(methylsulfanyl)-2-nitroethene (II) in boiling ethanol to give RGH-5981.
The reaction of N-methyl-4-piperidone (II) with phenyllithium (I) in benzene-ethyl ether below 10 C gives 4-hydroxy-1-methyl-4.phenypiperidine (III), which is dehydrated by treating with refuxing concentrated HCl.