Compound represented by formula (1) or a pharmaceutically acceptable solvate thereof, usefull for treating or preventing Paget's disease of bone, hypercalcmia, osteoporosis or asthma. (1) R1 represents a C1-C6alkyl group or C7-C15 aralkyl group (the aromatic ring of which can be substituted by a C1-C8 alkyl group, C1-C6 alkoxy group, a hydroxyl group, a halogenatom or a trifluoromethyl group), R2 represents a C1-C6 alkyl group, and R3 represents a C1-C6 alkyl or alkoxy group, which can be substituted with a hydroxyl group.
Compound represented by formula (1) or a pharmaceutically acceptable solvate thereof, useful for treating or preventing Paget's disease of bone, hypercalcaemia, osteoporosis or asthma. (1) R
1
represents a C
1
-C
6
alkyl group or C
7
-C
15
aralkyl group (the aromatic ring of which can be substituted by a C
1
-C
6
alkyl group, C
1
-C
6
alkoxy group, a hydroxyl group, a halogenatom or a trifluoromethyl group), R
2
represents a C
1
-C
6
alkyl group, and R
3
represents a C
1
-C
6
alkyl or alkoxy group, which can be substituted with a hydroxyl group.