| abstract |
There are provided crystals of a thiazolidinedione derivative having excellent prophylactic and therapeutic effects on a disease caused by insulin resistance and a process for producing the thiazolidinedione derivative with a high purity. A process for producing a compound represented by the general formula (A) or a salt thereof, comprising converting 4-[(2,4-dioxothiazolidin-5--yl)methyl]phenoxyacetic acid represented by the following formula into a compound of the general formula (I), wherein X = a halogen atom; then reacting the compound with a compound represented by the general formula (II), wherein R1, R2, R3 and R4 = a hydrogen atom, a hydroxyl group, C1-C6 alkyl, C1-C6 alkoxy, benzyloxy, acetoxy, trifluoromethyl or a halogen atom, R5 = C1-C6 alkyl, and R6 = a protecting group for an amino group, to produce a compound represented by the general formula (III); and subsequently cyclizing the compound into the final product, and crystals of a compound represented by the general formula (A) or a salt thereof. |