Abstract
A diphenylamine-linked bis(oxazoline) ligand with trans-diphenyl substitution on the oxazoline rings has been immobilized onto one- to three-generation Fréchet-type dendrimers and a C3-symmetric core structure. The catalytic activities and enantioselectivities of these new ligands were tested in the asymmetric Friedel-Crafts alkylation reactions of indole derivatives with, nitroalkenes. The two types of immobilized ligands exhibited similar enantioselectivities and substrate compatibilities to the free ligand trans-DPBO we reported previously. No dendrimer effect was observed in the kinetic investigation of the Fréchet-type dendrimer-immobilized ligands. The in situ recycling of the catalysts was also tested to illustrate the effect of reducing catalyst loading and the efficiency of our system.
Original language | English |
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Pages (from-to) | 2121-2131 |
Number of pages | 11 |
Journal | European Journal of Organic Chemistry |
Issue number | 11 |
DOIs | |
Publication status | Published - Apr 2010 |
Keywords
- Alkylation
- Dendrimers
- Friedel-crafts reaction
- Heterocycles
- Immobilization