| CPC C07D 221/08 (2013.01) [C07F 9/5765 (2013.01)] | 23 Claims |

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1. A compound according to formula (Id)
![]() or a pharmaceutically acceptable salt thereof,
wherein R1, R2 and R3 are according to a), b), or c) below:
a) R1 is substituent (i) below; and
R2 is selected from H, C1-C6 alkyl, benzyl and substituent (i) below;
and R3 is absent;
b) R1 is selected from H, C1-C6 alkyl, benzyl and substituent (i) below; and
R2 is substituent (i) below;
and R3 is absent;
![]() wherein * indicates the attachment point,
or
c) R1 and R2 are both H and R3 is substituent (ii) below, N is positively charged,
![]() and wherein * indicates the attachment point;
and wherein
R4 and R5 are each independently selected from H, C1-C6 alkyl, phenyl, benzyl, C3-C6 cycloalkyl and methyl substituted with C3-C6 cycloalkyl.
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