Benzofuran derivatives useful as inhibitors of bone resorption

A compound of the formula:

• ##STR16## wherein R.sup.1 is hydrogen, lower alkyl, an acyl group, amino, acylamino, nitro, halogen or hydroxy(lower)alkyl which may have one or more suitable substituent(s),
• R.sup.2 is lower alkyl or acyl(lower)alkyl,
• R.sup.3 is hydrogen, lower alkyl, lower alkenyl, cyclo(lower)alkyl(lower)alkyl, halogen, an acyl group, acyl(lower)alkyl, acylamino, acylamino(lower)alkyl, acyl(lower)alkenyl, acyloxy(lower)alkyl, acyl(lower)alkylthio(lower)alkyl, amino(lower)alkyl, mono- (or di-)lower alkylamino, lower alkylthio(lower)alkyl, mono-(or di)loweralkoxy(lower)alkyl which may have one or more suitable substituent(s), hydroxyimino(lower)alkyl which may have one or more suitable substituent(s), hydroxy(lower)alkyl which may have one or more suitable substituent(s), hydroxy(lower)alkylthio(lower)alkyl, lower alkyl substituted with heterocyclic group which may have one or more suitable substituent(s), heterocyclic group which may have one or more suitable substiutuents(s), or heterocyclicthio(lower)alkyl,
• in which R.sup.2 and R.sup.3 may be linked together to form
• (1) lower alkylene which may have one or more suitable substituent(s),
• (2) lower alkenylene which may have one or more suitable substituent(s), or
• (3) a group of the formula:
• ##STR17## wherein A.sup.1 and A.sup.2 are each lower alkylene which may have one or more suitable substituent(s), and ##STR18## W is wherein R.sup.5 is hydrogen, or an acyl group, and
• m and n are each an integer of 0 or 1,
• X is O
• Y is a group of the formula:
• --NHCO--,
• Z is aryl which may have one or more suitable substituent(s),
• l is an integer of 1,
• and a pharmaceutically acceptable salt thereof.