EP1284260A1 — Tyrosine phosphatase inhibitors

USPTO Abstract

A compound of the formula (I):    wherein X 1 and X 2 are the same or different and each is a bond or a spacer having 1 to 20 atom(s) in the main chain;    one of R 1 and R 2 is a cycle group having substituent(s) selected from 1) an optionally substituted carboxy-C 1-6 alkoxy group and 2) an optionally substituted carboxy-C 1-6 aliphatic hydrocarbon group, wherein the cycle group optionally has additional substituent(s), and the other is an optionally substituted cycle group or a hydrogen atom; and    R 3 , R 4 and R 5 are the same or different and each is a hydrogen atom or a substituent, or R 4 may link together with R 3 or R 5 to form an optionally substituted ring;    provided that when R 3 is a hydrogen atom, R 4 is a hydrogen atom and R 5 is methyl, X 2 -R 2 is not 4-cyclohexylphenyl; when R 3 is 4-methoxyphenyl, R 4 is a hydrogen atom and R 5 is methyl, X 2 -R 2 is not 4-methoxyphenyl; and when R 1 or R 2 is a hydrogen atom, the adjacent X 1 or X 2 is not a C 1-7 alkylene; or a salt thereof exhibits a protein tyrosine phosphatase inhibitory action and is useful as a prophylactic or therapeutic agent for diabetes or the like.