Jozef Hodyl PhD Thesis - Theses - Flinders University

agreed with literature values. 109Removal of the formyl groups was performed by stirring compound 53 insolution with 1 M HCl at 50 o C for five hours. The reaction mixture was thenconcentrated in vacuo to complete dryness and subsequently dissolved in EtOH,which was boiled for one hour. After cooling this solution, filtration (1 st crop) andprecipitation by addition of diethyl ether (2 nd crop) gave the trihydrochloride salt ofmono-cbz-protected cyclen, 50, in 96% yield, Scheme 2.4.5355 50Scheme 2.4 Preparation of the mono-N-protected cyclen synthon 50.The pH of an aqueous solution of 55 was then adjusted to ~13 by the drop-wiseaddition of ice-cooled 1M NaOH to give the basic form, 50, in 98% yield. The 1 HNMR and 13 C NMR spectra for both 55 and 50 show the disappearance of the broadpeaks for the three formyl groups and are in good agreement with literature values. 1092.4 Synthesis of the pendant armsHaving successfully prepared mono-protected cyclen, 50, with high purity and ingood yield, the next element in the sequential progression towards tri-N-alkylationwas to synthesise the epoxides that would be used to form the pendant arms.42