Patent ID: 8227473

Claim:
A compound having the structure wherein bond α is present or absent; R 1 and R 2 is each independently H, O − or OR 9 , where R 9 is H, alkyl, alkenyl, alkynyl or aryl, or R 1 and R 2 together are ═O; R 3 is O(CH 2 ) 2-6 R 9 or OR 10 , where R 10 is C 2-C 12 alkyl, alkenyl, alkynyl, aryl, R 4 is where X is O, S, NR 11 , or N + R 11 R 11 , where each R 11 is independently H, alkyl, hydroxyalkyl, C 2 - C 12 alkyl, alkenyl, C 4 -C 12 alkenyl, alkynyl, alkynyl, aryl, —CH 2 CN, —CH 2 CO 2 R 12 , —CH 2 C 0 R 12 or —NH 30 (R 12 ) 2 , where each R 12 is independently H, alkyl, alkenyl or alkynyl; R 5 and R 6 taken together are ═O; and R 7 and R 8 is each independently H, F, Cl, Br, SO 2 Ph, CO 2 CH 3 , or SR 13 , where R 13 is H, aryl, alkyl, alkenyl or alkynyl, or a salt, enantiomer or zwitterion of the compound.