Patent ID: 7598419

Claim:
A compound of Formula I, or a salt thereof: wherein R 1 and R 2 are both OH or R 1 and R 2 are both OCH 3 ; R 3 is selected from C 1-6 alkylCO 2 , C 1-6 alkyl(C═O)NH, or C 1-6 alkyl(C═O)N(C 1-6 alkyl); R 4 is selected from C(X)R 5 , SO 3 Ar, NH 2 , NH—C 1-6 alkyl, N(C 1-6 alkyl)(C 1-6 alkyl), P(O)(OH) 2 , P(O)(OC 1-6 alkyl) 2 , and C(NH 2 )═C(CN) 2 ; X is selected from O, S, NH and N—C 1-6 alkyl; R 5 is selected from NH 2 , OH, NH(CH 2 ) p Ar, NH(CH 2 ) p OH, (CH 2 ) p OC 1-6 alkyl, C 1-6 alkyl, C 1-6 alkoxy, NHNH 2 , NHC(O)NH 2 , NHC(O)C 1-6 alkoxy, N-morpholino and N-pyrrolidino; and Ar is an aromatic or heteroaromatic group, unsubstituted or substituted with 1-4 substituents, independently selected from OH, C 1-6 alkyl, C 1-6 alkoxy, NH 2 , NH—C 1-6 alkyl, N(C 1-6 alkyl)(C 1-6 alkyl), SH, S—C 1-6 alkyl, NO 2 , CF 3 , OCF 3 and halo; and p is 1-4.