Construction of Janus dendrimers through a self-assembly approach involving chiral discrimination at a focal point

Abstract

A strategy to build Janus dendrimers via the chirality-directed self-assembly of heteroleptic Zn(II) BOX complexes is reported. The method allows quantitative synthesis of Janus dendrimers in situ without the need...

Multi-Functionalization of Solid Support via Zn(II)-Mediated Chirality-Directed Self-Assembly

“…1 The process of selfassembly, 2 where building units of a system are organized into an ordered and/or functional structure, has attracted researchers from a diverse range of disciplines that varies from chemistry and material science to engineering and technology. 3 The assembly through covalent bonds 4 has the advantage of being independent of and unaffected by solvent conditions, such as solvent polarity and ionic strength. 5 However, the generation of covalent bonds often raises challenges due to the compatibility of reagents and reaction conditions for functional groups within building units.…”

“…The concept of chirality-directed self-assembly was also employed to quantitatively generate distinct Janus dendrimers in situ from various dendron subunits attached to chiral BOX ligands. 15 The highly selective formation of the heterochiral Zn(II) complex at the focal point of the Janus dendrimer enables the exclusive formation of Janus dendrimer upon mixing two distinct dendritic domains, each functionalized by opposite enantiomer of BOX ligands. The heterochiral Zn(II) BOX complex at the focal point was stable under elevated temperature.…”

“…Procedure for Immobilization of Chiral Bis(Oxazoline) Ligand (R,R)-SI-2 on Wang Resin. (Used in Table3)The chiral BOX ((R,R)-BOX (Ph)) immobilization was prepared according to the reported procedure.3 Briefly, to the suspended solution of SI-14 (1.01 g, 2.45 mmol) in dry DMF (75ml) was added K2CO3 (450 mg, 3.26 mmol) and 18-crown-6 (90 mg, 0.326 mmol) at 0 o C. The reaction mixture was warmed to room temperature and stirred for 2 hours. The reaction was cooled to 0 o C and Wang-Br resin (0.5-1 mmol/g, 2.40 g) was added in one portion.…”

Chirality-driven self-assembly: application toward renewable/exchangeable resin-immobilized catalysts

“…We recently reported using this high selectivity to generate structurally distinct Janus dendrimers quantitatively in one-pot process. 17 Prior studies used the strategy to construct supramolecular chiral bidentate ligands in various asymmetric reactions. 18 We now report applying a similar approach to loading catalysts on to a solid resin support.…”