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Screening of a Phosphite–Phosphoramidite Ligand Library for Palladium‐Catalysed Asymmetric Allylic Substitution Reactions: The Origin of Enantioselectivity
Author(s) -
Pàmies Oscar,
Diéguez Montserrat
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700852
Subject(s) - phosphoramidite , ligand (biochemistry) , allylic rearrangement , chemistry , moiety , palladium , substitution reaction , combinatorial chemistry , substrate (aquarium) , stereochemistry , catalysis , organic chemistry , receptor , dna , biochemistry , oligonucleotide , oceanography , geology
We have designed a new library of readily available, highly modular phosphite‐phosphoramidite ligands for asymmetric allylic substitution reactions. They are easily prepared in one step from commercially available chiral 1,2‐amino alcohols. The introduction of a phosphoramidite moiety into the ligand design is highly advantageous for the product outcome. This ligand library affords high reaction rates (TOFs of up to 800 mol (mol h) −1 ) and enantioselectivities ( ee s of up to 99 %) and, at the same time, contains a broad range of disubstituted hindered and unhindered substrate types. NMR study of the Pd‐π‐allyl intermediates provide a deeper understanding of the effect of the ligand parameters on the origin of enantioselectivity.