Patent ID: 6911467

Claim:
A compound according to the general formula 1, or a pharmaceutically acceptable salt thereof, wherein A is and R 1 is selected from H, C 1 -C 6 alkyl, (CH 2 ) a NHW 1 , (CH 2 ) b COW 2 , (CH 2 ) c OW 3 , CH(Me)OW 4 , (CH 2 ) d —C 6 H 4 —W 5 , and (CH 2 ) e SW 6 , where a is 2-5, b is 1-4, c is 1-2, d is 1-2, e is 1-3; W 1 is COW 6 , CO 2 W 6 , or SO 2 W 6 ; W 2 is OH, NH 2 , OW 6 , or NHW 6 ; W 3 is H or W 6 ; W 4 is H or W 6 ; W 5 is H, OH, or OMe; and W 6 is C 1 -C 6 alkyl, benzyl, optionally substituted phenyl, or optionally substituted heteroaryl, where the optional substituents are one or two groups selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, F, and Cl; R 2 is H or —(CH 2 ) n NH—C 5 H 3 N—Y, where n is 2-4 and Y is selected from H, F, Cl, NO 2 , and CN, or R 1 and R 2 together are —(CH 2 )p-, where p is 3 or 4; X is selected from (i) L-alpha-amino acyl groups selected from Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, and Tyr; (ii) groups R 3 CO, where R 3 is H, C 1 -C 6 alkyl, or phenyl; (iii) groups R 4 COOC(R 5 )(R 6 )OCO, where R 4 is H, C 1 -C 6 alkyl, benzyl, or optionally substituted phenyl which may include up to two substituent groups selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, F, and Cl; and R 5 and R 6 are independently H or C 1 -C 6 alkyl, or R 5 and R 6 together are —(CH 2 ) m — where m is an integer of 4-6; and (iv) methoxycarbonyl, ethoxycarbonyl, and benzyloxycarbonyl groups.