Abstract: The present invention relates to ethyl (2S)-2-(naphthalene-1-sulfonylamino)-3-(4-(2-(1,4,5,6-tetrahydropyrimidin-2-ylcarbamoyl)ethyl)benzoylamino)propionate hemifumarate of formula (I), and to a process for its preparation comprising reacting 4-(2-(1,4,5,6-tetrahydropyrimidin-2-ylcarbamoyl)ethyl)benzoic acid or a derivative thereof and ethyl (2S)-3-amino-2-(naphthalene-1-sulfonylamino)propionate. The compound of formula (I) is a valuable pharmaceutical which can be used, for example, in the treatment or prophylaxis of diseases which can be influenced by inhibiting the vitronectin receptor, in particular of bone diseases such as osteoporosis. The invention furthermore relates to chemical intermediates useful for the preparation of the compound of formula (I).