| abstract |
It is intended to provide an Hsp90 family protein inhibitor, etc. comprising as the active ingredient a cyclic phenylacetic acid derivative represented by the following general formula (I), which is useful as drugs such as an antitumor agent, or its pharmacologically acceptable salt: (I) wherein R1, R2, R3 and R4 are the same or different and each represents hydrogen, hydroxy, optionally substituted lower alkyl, etc.; X represents oxygen, sulfur, -N(R5)- or -CH2-; a represents -CRa1Ra2-, optionally substituted arylene, an optionally substituted divalent heterocyclic group or a bond; b represents -(CRb1Rb2)m- or -CHRb3CRb4Rb5-; c represents -(CRc1Rc2)n(CHRc3CRc4Rc5)p-; d represents -(CRd1CRd2)q- or -CHRd3CRd4Rd5-; and e represents -CRe1Re2-. |