Sugar-based diphosphoroamidite as a promising new class of ligands in Pd-catalyzed asymmetric allylic alkylation reactions.
We have designed a new family of readily available modular diphosphoroamidite ligands from d-xylose for Pd-catalyzed asymmetric allylic alkylation reactions. This constitutes the first example of diphosphoroamidite ligands applied to this process. Good-to-excellent activities (TOFs up to 850 mol substratex(mol Pdxh)-1) and enantioselectivities (ee's up to 95%) have been obtained for several substrates with different electronic and steric properties. The results indicate that catalytic performance is highly affected by the substituents and the axial chirality of the biaryl moieties of the ligand. We also discuss the synthesis and characterization of the Pd-pi-allyl intermediates to get more insight into the origin of enantioselectivity using these catalytic systems.
Raluy
Eva
E
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Campus Sescelades, C/ Marcel lí Domingo, s/n, 43007 Tarragona, Spain.
Diéguez
Montserrat
M
Pàmies
Oscar
O