| 摘要 |
A compound of formula (I): <CHEM> wherein R<1> is CO2-, CO2H or CO2R<5> wherein R<5> is a group such that the grouping CO2R<5> is a pharmaceutically acceptable in vivo hydrolysable ester; H<2>, R<3> and R<4> independently represent a C1-12 hydrocarbon group optionally substituted with a functional substituent; Z- is a negatively charged ion; and n is zero or one such that the compound of formula (I) is electronically neutral. Their preparation and use is disclosed. |
