Compounds of the formula ##STR1## wherein X in each of formulas (1) and (2) represents a substituted or unsubstituted alkylene, alkenylene, or alkynylene linker of 2-6 C;Y represents one or more carbocyclic or heterocyclic rings; when two or more rings are present in Y, they may optionally be fused; andR' represents a cation, H or a substituted or unsubstituted alkyl group of 1-6 C; andthe dotted lines represent optional .pi.-bonds,promote bone formation and are thus useful in treating osteoporosis, bone fracture or deficiency, primary or secondary hyperparathyroidism, periodontal disease or defect, metastatic bone disease, osteolytic bone disease, post-plastic surgery, post-prosthetic joint surgery, and post-dental implantation. These compounds can be used in combination with other bone growth-promoting compounds and/or estrogens and/or bisphosphonates for this purpose.