Parallel and Modular Synthesis of P-Chirogenic P,O-Ligands

Magnus Johansson; Susanne Berglund; Yinjun Hu; Kristian Andersson; Nina Kann

doi:10.1021/co2002119

Parallel and Modular Synthesis of P-Chirogenic P,O-Ligands
Journal article, 2012

A modular synthesis of P-chirogenic alpha-alkoxyphosphine ligands has been developed, allowing for the variation of two of the three groups on phosphorus. Oxidation and concomitant desymmetrization of a prochiral alkyl- or aryldimethylphosphine borane afforded alpha-hydroxyphosphines, which were subsequently. deprotonated and alkylated in a parallel fashion. The choice of base and temperature for the alkylation step was found to be crucial for the outcome of the reaction. Selected ligands were subsequently screened in palladium catalyzed allylic substitution, affording product in good to excellent yield but moderate enantioselectivity, indicating that further optimization of the ligand structures is desirable to increase the stereoselectivity.

parallel synthesis

diphosphine ligands

catalyzed desymmetrization

stereogenic

phosphines

O-alkylation

chiral phosphine

phosphine-ligands

enantioselective conjugate addition

palladium catalyzed allylic substitution

phosphoramidite-ligands

combinatorial libraries

P-chiral

phosphorus ligands

solid-phase synthesis

asymmetric-synthesis