Patent ID: 6919455

Claim:
A compound represented by the following formula (I), or a salt thereof: where X is a halogen atom or a group represented by —S—(CH 2 ) n —A, —SO—(CH 2 ) m —B, —SO 2 —(CH 2 ) m —B, —OSO 2 —(CH 2 ) m —B, —OCO—(CH 2 ) m —B or —OPO(OR)—(CH 2 ) m —B, wherein n represents an integer of 0-4, A represents an optionally substituted aromatic hydrocarbon group or an optionally substituted heterocyclic residue having 1 to 4 hetero atoms selected from an oxygen atom, sulfur atom and nitrogen atom and having 5 to 10 ring-constituent atoms, m represents an integer of 0-4, B represents an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group or an optionally substituted heterocyclic residue having 1 to 4 hetero atoms selected from an oxygen atom, sulfur atom and nitrogen atom and having 5 to 10 ring-constituent atoms, and R represents an optionally substituted alkyl group.