Abstract Several new alkyl (147, 161 and 167) and alkoxy-methyl derivatives (171, 175) were prepared as analogues of the anti-tumour agent tirapazamine (38). These were prepared in an attempt to couple them to the pro-drug delivery agent 52. The bicyclic guanidine natural product monalidine A (186) was prepared as its hydrochloride salt from 2-undecanone via a novel 3-step synthesis. The biological activity of monalidine A (186) and one of its synthetic precursors were evaluated against Leishmaniasis infantum and Trypanosoma cruzi. Research towards the total synthesis of the tricyclic arbusculidine A (187) from cucumber aldehyde is reported.