A Library of Peralkylated Bis‐guanidine Ligands for Use in Biomimetic Coordination Chemistry

Abstract

Keywords: Nitrogen donor ligands / Guanidine ligands / Ligand designA series of bis-guanidine ligands designed for use in biomimetic coordination chemistry has been extended to a library matrix combining unprecedented substitutional flexibility within the guanidyl residues with a wide range of aliphatic and aromatic spacers connecting these functionalities. The underlying protocol can be used with predefined ureas as well as secondary amines to build up these units by reaction with phosgene if the ureas are otherwise unavailable. In the latter case, the resulting urea intermediates do not have to be isolated as the reaction proceeds further with additional phosgene to yield a chloroformamidinium chloride which is transformed into the bis-guanidine functionality by subsequent reaction with a suitable primary diamine in the presence of triethylamine as an auxiliary base. This concept has been used to synthesise and characterise more then two dozen different bis-guanidines based on 12 discrete monoguanidine units and seven different spacers. These spacers have been chosen such that the most important phenotypes have been dealt with and which range from rigid to more flexible scaffolds. In addition to spacers with no metal-bind-

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

“…All chemicals were used as purchased, besides styrene, which was destabilized by eluting through a column of neutral Al 2 O 3 . The Vilsmeier salts, N,N′-dimethylethylenechloroformamidinium chloride (DMEG) and N,N,N′,N′-tetramethylchloroformamidinium chloride (TMG), were synthesized as described in the literature [11,26]. The ligands DMEGpy and TMGpy were synthesized according to the protocol in the literature [27].…”

“…The modular synthetic protocol allows for the combination of different spacers, amine groups and guanidine groups for building up a ligand library [11]. The donor properties can be tuned through the choice of guanidine substituents, amine and spacers.…”

Quinine‐Derived Imidazolidin‐2‐imine Ligands: Synthesis, Coordination Chemistry, and Application in Catalytic Transfer Hydrogenation

“…Poly(guanidine) ligands [10] have found exceptional applications as superbasic proton scavengers [11] and as ligands for transition metal complexation [12], in particular in copper chemistry and dioxygen activation [13,14]. Moreover, monoand bis(guanidine) chelate ligands were used for the preparation of homogeneous catalysts, e.g.…”

Reactivity of Zinc Halide Complexes Containing Camphor-Derived Guanidine Ligands with Technical rac-Lactide

“…One new monoamine-hybridguanidine ligand 3-((1,3-dimethylimidazolidine-2-ylidene)amino)-1, 2,2-trimethylcyclopentane-1-amine (DMEGca) and the recently published ligand 2-(3-amino-2,2,3-trimethylcyclopentyl)-1,1,3,3-tetramethylguanidine (TMGca) [75] based on camphoric acid were prepared by the reaction of the corresponding Vilsmeier salt N,N -dimethylethylenechl oroformamidiniumchloride or N,N,N ,N -tetramethyl-chloroformamidiniumchloride with the diamine [76,77]. First the (1R, 3S)-camphor-bisamine has to be generated on the basis of (1R, 3S)-camphor acid via a Curtius rearrangement [75].…”

“…First the (1R, 3S)-camphor-bisamine has to be generated on the basis of (1R, 3S)-camphor acid via a Curtius rearrangement [75]. The addition of one equivalent of Vilsmeier salt and the presence of trimethylamine leads to the monoamine-guanidine hybridligands L1 (TMGca) and L2 (DMEGca) [76,77] (Figure 1). …”