A new class of modular P,N-ligand library for asymmetric Pd-catalyzed allylic substitution reactions: a study of the key Pd-pi-allyl intermediates.
A new class of modular P,N-ligand library has been synthesized and screened in the Pd-catalyzed allylic substitution reactions of several substrate types. These series of ligands can be prepared efficiently from easily accessible hydroxyl-oxazole/thiazole derivatives. Their modular nature enables the bridge length, the substituents at the heterocyclic ring and in the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety to be easily and systematically varied. By carefully selecting the ligand components, therefore, high regio- and enantioselectivities (ee values up to 96 %) and good activities are achieved in a broad range of mono-, di-, and trisubstituted linear hindered and unhindered substrates and cyclic substrates. The NMR spectroscopic and DFT studies on the Pd-pi-allyl intermediates provide a deeper understanding of the effect of ligand parameters on the origin of enantioselectivity.
Mazuela
Javier
J
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, C/Marcel líDomingo, s/n. 43007 Tarragona, Spain.
Paptchikhine
Alexander
A
Tolstoy
Päivi
P
Pàmies
Oscar
O
Diéguez
Montserrat
M
Andersson
Pher G
PG
D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D008024:Ligands; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
D000498:Allyl Compounds; D008024:Ligands; D010165:Palladium