A compound of the formula ##STR1## wherein R.sup.1 is hydrogen or hydroxy, R.sup.2 and R.sup.3 are independently hydrogen or lower alkyl and Y is carboxyl or a group convertible to carboxyl is effective for prevention or treatment of osteoporosis.
A compound of the formula
wherein R1 is hydrogen or hydroxy, R2 and R3 are independently hydrogen or lower alkyl and Y is carboxyl or a group convertible to carboxyl is effective for prevention or treatment of osteoporosis.