Receptor function regulating agent

A compound represented by the formula:

• wherein Ra is a fluorine atom, or a C1-6 alkoxy group
• Rb is a hydrogen atom, or a fluorine atom;
• Rc is a hydrogen atom, or a C1-6 alkyl group;
• Xa is an oxygen atom;
• ring C is a benzene ring optionally having, in addition to Rd and Re, further substituent(s) selected from the group consisting of (i) a C1-6 alkyl group, (ii) a hydroxy group, (iii) a C1-6 alkoxy group having substituent(s) selected from the group consisting of hydroxy, amino, C1-6 alkoxy-carbonyl-amino, carboxy, C1-6 alkoxy-carbonyl, carbamoyl, mono-C1-6 alkyl-carbamoyl, di-C1-6 alkyl-carbamoyl, and tri-C1-6 alkylsilyloxy, (iv) a C6-14 aryloxy group, and (v) a C7-16 aralkyloxy group;
• and
• one of Rd and Re is a hydrogen atom,
• (1) when Rd is a hydrogen atom,
• then Re should be (i) a hydroxy group, (ii) a C1-6 alkoxy group having substituent(s) selected from the group consisting of C1-6 alkoxy, carboxy, C1-6 alkoxy-carbonyl, C1-6 alkyl-carbonyl, carbamoyl, mono-C1-6 alkyl-carbamoyl, and di-C1-6 alkyl-carbamoyl, (iii) a C2-6 alkynyloxy group, (iv) a C3-7 cycloalkyloxy group, (v) a C6-14 aryloxy group optionally having substituent(s) selected from the group consisting of a halogen atom, C1-6 alkyl, C1-6 alkoxy, and C1-6 alkyl-carbonyl, or (vi) a 5- to 10-membered heterocyclyl-oxy group containing, in addition to carbon atom(s), 1 to 4 heteroatoms of one or two kinds selected from a nitrogen atom, a sulfur atom and an oxygen atom;
• (2) when Re is a hydrogen atom,
• then Rd should be, (i) a C6-14 aryl group, (ii) a C3-7 cycloalkyloxy group, (iii) a C6-14 aryloxy group optionally having substituent(s) selected from the group consisting of a halogen atom and optionally halogenated C1-6 alkyl, (iv) a C7-16 aralkyloxy group, or (v) a 5- to 7-membered heterocyclic group containing, in addition to carbon atom(s), 1 to 4 heteroatoms of one or two kinds selected from a nitrogen atom, a sulfur atom, and an oxygen atom,
• or a salt thereof.