| 摘要 |
<p>Compounds of the general formula (|) or salts thereof exhibit a protein tyrosine phosphatase inhibiting activity and are useful as preventive and therapeutic drugs for diabetes or the like: (|) wherein X1 and X2 are each a free valency or a spacer having a C1-20 main chain; one of R1 and R2 is a cyclic group which bears a substituent selected from among (1) carboxylated C1-6 alkoxy groups which may be substituted and (2) carboxylated C1-6 aliphatic hydrocarbon groups which may be substituted and may further have other substituent, and the other is an optionally substituted cyclic group or hydrogen; and R3, R4 and R5 are each hydrogen or a substituent, or alternatively R4 together with R3 or R5 may form an optionally substituted ring, with the proviso that some compounds of the general formula (|) are excepted.</p> |
