Jozef Hodyl PhD Thesis - Theses - Flinders University

21R 1 = protecting group 1R 2 = protecting group 2R 3 = pendant armScheme 2.1: Five step synthetic strategy for tri-N-alkylation of cyclen, 21.It can be seen conceptually in Scheme 2.1 that synthesis of a tri-N-alkylatedcyclen derivative requires five steps involving protection with two differentprotecting groups and subsequent deprotection to achieve the desired alkylationpattern on the cyclen skeleton.2.3.1 Synthesis of tri-formyl protected cyclenSynthesis of the mono-N-protected cyclen used in this work commenced withpreparation of a cyclen derivative with three of the four available N-positionsprotected with formyl groups as depicted in Scheme 2.2.21 52Scheme 2.2 Synthesis of the tri-N-formylated cyclen, 52.39