Patent ID: 7001895

Claim:
A compound of formula I: or a pharmaceutically acceptable salt or ester thereof, wherein: X is selected from the group consisting of O; R is a phenyl optionally substituted with 1, 2, 3, 4, or 5 substituents each independently selected from the group consisting of halogen, alkyl, and haloalkyl; R 1 is selected from the group consisting of phosphonatoalkoxy, carboxyalkylcarbonyloxyalkoxy, and aminoalkylcarbonyloxyalkoxy; R 3 is hydrogen; R 2 is a group of the structure: X 1 is S(O) 2 ; X 2 is selected from the group consisting of hydrogen, halogen, and alkyl; and R 9 is selected from the group consisting of alkyl and amino.