New Macrocyclic Ligands. VII. The Synthesis of Mixed-Donor Spiro-Linked Macrocycles

Abstract

The syntheses of five new spiro -linked bis-macrocyles, incorporating four ether oxygen and four or six secondary nitrogen heteroatoms , are reported. Two strategies were employed-the first involved the condensation of a spiro tetraaldehyde with 2 equiv. of ethane-1,2-diamine or propane-1,3-diamine or 2,2′-diaminodiethylamine followed by in situ reduction of the resulting intermediate tetraimines . The second procedure began with pentaerythrityl tetraamine [C(CH₂NH₂)₄] which was then condensed with 2 equiv. of a dialdehyde moiety in which two ether oxygen atoms, bridged by either two or three methylene groups, were incorporated in its backbone. A related in situ reduction step to that employed in the first procedure then yielded the required double-ring macrocycles. For use in comparative studies, the corresponding single-ring macrocycles were also synthesized where they had not been reported previously.