2-{2-[2-(Ethoxy-methyl-phosphinothioylsulfanyl)-acetylamino]-acetylamino}-propionic acid ethyl ester
2-{2-[2-(Ethoxy-methyl-phosphinothioylsulfanyl)-acetylamino]-acetylamino}-3-methyl-butyric acid ethyl ester
{2-[2-(Ethoxy-methyl-phosphinothioylsulfanyl)-acetylamino]-acetylamino}-acetic acid ethyl ester
3-{2-[2-(Ethoxy-methyl-phosphinothioylsulfanyl)-acetylamino]-acetylamino}-propionic acid ethyl ester