905571-01-9Relevant academic research and scientific papers
Synthesis and application of chiral N-heterocyclic carbene-oxazoline ligands: Iridium-catalyzed enantioselective hydrogenation
Nanchen, Steve,Pfaltz, Andreas
, p. 4550 - 4558 (2006)
Two libraries of enantiomerically pure imidazolium salts bearing an oxazoline unit were synthesized. Deprotonation of the imidazolium salts and complexation of the resulting oxazoline-carbene ligands to iridium(i) was achieved in one step by mixing the im
Modular phosphite-oxazoline/oxazine ligand library for asymmetrie Pd-catalyzed allylic substitution reactions: scope and limitations - origin of enantioselectivity
Dieguez, Montserrat,Pamies, Oscar
experimental part, p. 3653 - 3669 (2009/04/23)
A library of phosphite-oxazoline/oxazine ligands L1-L15a-h 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 amino acid derivatives. Their modular nature enables the substituents/configurations in the oxazoline/oxazine moiety, alkyl backbone chain and 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 99%) and good activities have been achieved in a broad range of mono- and disubstituted linear hindered and unhindered liner and cyclic substrates. The NMR studies on the Pd-π-allyl intermediates provide a deeper understanding about the effect of the ligand parameters on the origin of enantioselectivity. It also indicates that the nucleophilic attack takes place predominantly at the allylic terminal carbon atom located trans to the phosphite moiety.
