Ethyl 5 - [bis (2-hydroxyethyl) amino] - 1-methyl-1h-benzimidazole-2-butyrate, also known as 4 - {5-Bis - (2-hydroxyethyl) amino] - 1-methyl-2-benzimidazole} butyrate, is an intermediate in the synthesis of bendamustine hydrochloride. Bendamustine hydrochloride was first developed by ozegowski and his colleagues in the early 1860s at the experimental Society for microbiology in Jena, Germany. Its original purpose was to make an alkylated nitrogen mustard connect a purine and an amino acid.