for the following products
4-(Aminothioxomethyl)-1-piperazinecarboxylic acid 1,1-dimethylethyl ester | 4-Thiocarbamoyl-piperazine-1-carboxylic acid tert-butyl ester | tert-Butyl 4-carbamothioylpiperazine-1-carboxylate and 4-(tert-Butoxycarbonyl)piperazine-1-thicarboxamide
