| abstract |
A compound of formula (I): n n n n n n n n n n or a salt, solvate and chemically protected form thereof, wherein one of R 2 and R 5 is:n (i) H or an optionally substituted C 1-4 alkyl group; or (ii) an optionally substituted C 5-7 aryl; and the other of R 2 and R 5 is the other group; m and n can be 0 or 1, and m+n=1 or 2 R N is H or optionally substituted C 1-4 alkyl R 3 is either: (i) carboxy; (ii) a group of formula (II): nn n n n n n n n n n (iii) a group of formula (III): n n n n n n n n n n n n wherein R is optionally substituted C 1-7 alkyl, C 5-20 aryl, or NR N3 R N4 , where R N3 and R N4 are independently selected from optionally substituted C 1-4 alkyl; orn (iv) tetrazol-5-yl. |