The present invention relates to novel compounds formed by metabolic conversion of compounds of structural formula (1), pharmaceutical compositions containing such compounds, and their use as &agr;v&bgr;3 integrin receptor antagonists. The compounds of the present invention are useful for inhibiting bone resorption, restenosis, angiogenesis, diabetic retinopathy, macular degeneration, inflammatory arthritis, cancer, and metastatic tumor growth. They are particularly useful for inhibiting bone resorption and for the treatment and prevention of osteoporosis.