for the following products
4-[2-(Ethoxycarbonyl)-5-benzofuranyl]-1-piperazinecarboxylic acid tert-butyl ester | Ethyl 5-(4-tert-butoxycarbonyl-1-piperazinyl)benzofuran-2-carboxylate and tert-Butyl 4-(2-(ethoxycarbonyl)benzofuran-5-yl)piperazine-1-carboxylate