Patent ID: 7608603

Claim:
A compound of formula Ia: or a pharmaceutically acceptable salt thereof, wherein: R 1 is optionally substituted phenyl; R 2 is optionally substituted phenyl R 4 is hydroxyalkyl, alkoxyalkyl or alkylsulfonylalkyl R 5 is hydrogen, —C(═O)—R c , —(O═)P(OR d ) 2 , —S(═O) 2 OR d , or a mono-, di- or tri-peptide; wherein R c is —(CH 2 ) p —C(═O)—R e ; wherein R e is hydrogen, hydroxy, alkoxy or amine; p is 2 or 3; R d is hydrogen, alkyl, an alkali metal ion or an alkaline earth metal ion; X and Y are nitrogen; D is —(CR 7 R 8 ) n —; wherein n is from 1 to 3; R 7 and R 8 each independently is hydrogen or alkyl; W is a bond or NR i ; R i is hydrogen; A is O; and k is 0.