Synthesis and characterisation of a mesocyclic tripodal triamine ligand

Abstract

Meso-- and macrocyclic polydentate amine ligands have been widely explored in oxidation catalysis and for the stabilization of unstable metal--superoxide, --peroxide, and --oxo intermediates. Herein we report on the design and synthesis of a novel mesocyclic, tripodal, triamine ligand that we believe will be an excellent addition to this field. We explored a number of synthetic procedures towards the mesocyclic asymmetric tetraalkylated ligand 1. We expect that 1 will bind metals in a facially capping manner, yielding complexes that display pseudo--tetrahedral geometry, potentially providing access to unprecedented late transition metal--oxo complexes (metal = Co, Ni, Cu). We describe the preparation of a library of mescocylcic polyamine synthons (8, 16, 17, 18, 19) that are precursors in the synthesis of 1. These synthons will be used to tailor the electronic properties of metal complexes of 1 and derivatives thereof. The X--ray crystal structures of 19 and mono-- and di--protonated forms of 1b show that the triamine crystalises in a boat--chair conformation which is undesirable for metal coordination.

Use of Light-Degradable Aliphatic Polycarbonate Nanoparticles As Drug Carrier for Photosensitizer

“…The six-membered cyclic carbonate monomer LrM was prepared from 2-(hydroxymethyl)-2-methylpropane-1,3-diol following the synthetic route as shown in Scheme . In a four-step reaction, one hydroxy group ( 1 ) was converted into an amino group ( 4 ). − Amine 4 was then protected with the light-cleavable 4,5-dimethoxy-2-nitrobenzyl group via a carbamate linkage to give compound 5 . The acetal 5 was hydrolyzed with HCl to reveal the diol 6 , which was cyclized with ethyl chloroformate to form the cyclic LrM .…”

“…Compound 4 was synthesized similar to the literature. 42 Compound 3 (9.26 g, 50 mmol) and ammonium formate (12.6 g, 200 mmol) were dissolved in dry MeOH (130 mL). The solution was purged with argon for 20 min.…”

Unexpected Intramolecular Phosphite‐Mediated Amide Coupling To Yield 3,5‐Dioxo‐1‐Piperazines

“…[4] This could allow for the preparation of late transition M=O species, such as Ni IV = O. [5] Herein we report on studies towards tripodal tris-anionic carboxamidate ligands for late transition M=O species.…”