Abstract: A method for manufacturing a 6-substituted 1-methyl-1H-benzimidazole derivative represented by the formula (IV) wherein R3 represents a hydrogen atom or a C1-C4 alkyl group. A 4-substituted N2-methylbenzene-1,2-diamine derivative is prepared from a particular 5-substituted N-methyl-2-nitroaniline derivative, subsequently reacting the resulting compound with {4-[(2,4-dioxo-1,3-thiazolidin-5-yl)methyl]phenoxy}acetic acid or an acid chloride or a mixed acid anhydride thereof, and subsequently subjecting the resulting compound to intramolecular dehydration condensation. A compound of the formula (II) wherein R1 represents a hydrogen atom, a C1-C4 alkyl group, or a protective group for the nitrogen atom, and R2 represents a hydrogen atom or a protective group for the nitrogen atom is prepared and used as an intermediate.

Abstract: A compound which is 5-{4-[(6-methoxy-1-methyl-1H-benzimidazol-2-yl)methoxy]benzyl}thiazolidine-2,4-dione hydrochloride, in crystal form wherein a powder x-ray diffraction pattern obtained by irradiation with a Cu K? line shows main peaks at interplanar spacings d=14.29, 7.12, 5.34, 4.97, 4.74, 3.95, 3.85, 3.75, 3.55, 3.51, 3.15, 2.84, 2.76, 2.52 and 2.37.

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.