| abstract |
A compound of structure IX or X: ** Formula ** Structure IX Structure X or a pharmaceutically acceptable salt thereof, wherein: X is -C (> = O) N (R10) - or -CH (OPr3) -; R7, R9 and R10 are the same or different and mean hydrogen or a natural or unnatural amino acid side chain residue; Pr1 and Pr2 are the same or different and mean hydrogen or a thiol protecting group; Pr3 is hydrogen or an alcohol protecting group; R1, R2, R5 and R6 are the same or different and mean hydrogen or a natural or unnatural amino acid side chain residue, or R1 and R2 and / or R5 and R6, taken together with the carbon atom to which they are attached , form a spirocyclic moiety; each amino acid side chain residue of an unnatural amino acid is independently selected from (CR11R11) x-NR11C (O) NR11R11, - (CR11R11) x-NR11C (O) NR11R13, - (CR11R11) x-NR11C (O) OR14, - (CR11R11) x-NR11C (O) R14, - (CR11R11) x-NR11C (O) R13, - (CR11R11) x-NR11SO2NR11R11, - (CR11R11) x-NR11SO2NR11R13, - (CR11R11) x-NR11SO3R14, - (CR11R11) x-NR11SO2R14, - (CR11R11) x-NR11SO2R13, - (CR11R11) xC (O) NR11R11, - (CR11R11) xC (O) NR11R13, - (CR11R11) x-CO2R11, - (CR11R11) xC ( O) R13, - (CR11R11) x-SO2NR11R11, - (CR11R11) x-SO2NR11R13, - (CR11R11) x-SO2R13, - (CR11R11) x-Ar, -CH2-CH2OH (homoserine) or - (CH2) 3NH2 ( ornithine). |