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The synthesis and metal complexation of chiral depsipeptide dendrimers 3 and 7 containing an ethylenediaminetetraacetic acid (EDTA) ester‐derived core is reported. The EDTA ester cavity of these dendrimers selectively complexes Zn2+ and Cu2+ ions leading to diastereoselective folding. To elucidate the coordination motif in the resulting “foldamers” of 3‐ZnCl2, 7‐ZnCl2, 3‐CuCl2, and 7‐CuCl2, the coordination behavior of the tetramethyl ester of EDTA (8) has been investigated as a model case. The corresponding complexes 8‐ZnCl2 and 8‐CuCl2 have been structurally characterized by 1H NMR spectroscopy and X‐ray analysis. The complexes involve the inherently chiral octahedral cis‐α coordination motif, in which 8 serves as a tetradentate ligand. In the case of the ZnII complex 8‐ZnCl2, both Δcis‐α(S,S,λ) and Λcis‐α(R,R,λ) stereoisomers were found in the unit cell. For the CuII complex 8‐CuCl2, only one stereoisomer, namely Δcis‐α(S,S,λ) was found in the crystal under investigation. 1H NMR spectroscopy has shown that the same coordination motif is diastereoselectively formed in the chiral Zn2+ dendrimers 3‐ZnCl2 and 7‐ZnCl2. Likewise, the calculated CD spectrum of the Δcis‐α(S,S,λ) stereoisomer of the model complex 8‐CuCl2 shows good agreement with the experimental spectrum of the CuII dendrimers 3‐CuCl2 and 7‐CuCl2, allowing assignment of the absolute configurations of the preferred foldamers as Λcis‐α(R,R,λ) for 3‐CuCl2 and Δcis‐α(S,S,λ) for 7‐CuCl2. This work represents the first example of metal‐complexation‐mediated diastereoselective folding of chiral dendrimers with known absolute configuration.

The synthesis, characterization and chiroptical properties of chiral dendrimers 11-14 formed by ruthenium coordination of2,2Ј-bipyridine (bpy*) ligands 4, 7, 8 and 10 involving two pairs of enantiomerically pure depsipeptide dendrons bound in 4,4Ј-position are described. In the case of the first and second generation ligands 4, 7 and 8 the metallodendrimers 11, 12 and 13 are formed containing a central [Ru(bpy*) 3 ] 2+ core. After coordination of the third generation dendritic ligand 10 the metallodendrimer 14 with two bpy* ligands, {[Ru(bpy*) 2 -Cl 2 ] core} was isolated. The corresponding metallodendrimer 15 with three bpy* ligands was formed in traces only. Dendrimers 11, 12 and 13 are the first chiral metallodendrimers involving an [Ru(bpy*) 3 ] 2+ core. This chiral coordination motif can have either a ∆ or a Λ configuration. To elucidate if there

Both enantiomers of an optically active trialkynyl(phenyl)methane (the key building blocks in the construction of a stable expanded cubane) have been prepared. The strategy involved the resolution of a racemic intermediate by means of HPLC on a chiral stationary phase. The absolute configuration of this intermediate was unambiguously assigned by using vibrational circular dichroism (VCD) and optical rotatory dispersion (ORD), in combination with density functional theory (DFT) calculations.

DendrimersDendrimers O 0450 Synthesis and Chiroptical Properties of a New Type of Chiral Depsipeptide Dendrons. -(BUSCHHAUS, B.; BAUER, W.; HIRSCH*, A.; Tetrahedron 59 (2003) 22, 3899-3915; Inst. Org. Chem., Friedrich-Alexander-Univ., D-91054 Erlangen, Germany; Eng.) -Lindner 33-070