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Phosphoramidite Ligands Based on Simple 1,2‐Diols: Synthesis, Use in Copper‐Catalyzed Asymmetric Additions, and Achirotopic Stereogenic Phosphorus Centres
Author(s) -
Mistry Nisha,
Fletcher Stephen P.
Publication year - 2016
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201600368
Subject(s) - phosphoramidite , stereocenter , chemistry , diastereomer , ligand (biochemistry) , catalysis , enantioselective synthesis , amine gas treating , combinatorial chemistry , stereochemistry , organic chemistry , medicinal chemistry , dna , biochemistry , receptor , oligonucleotide
Phosphoramidite ligands are widely used in catalysis and normally constructed from large C 2 ‐symmetrical diols such as BINOL or TADDOL. We report here on new ligands based on a set of simple diols that had been previously overlooked. Ligands based on ( S,S )‐ trans ‐cyclohexanediol and ( R,R )‐(+)‐1,2‐diphenyl‐1,2‐ethanediol, in combination with both chiral and achiral amines, were tested in 3 different copper‐catalyzed asymmetric reactions and up to 89% ee was observed. A different ligand gave the best results in each reaction examined. Using meso ‐ cis‐ cyclohexanediol and meso‐cis‐ diphenyl‐1,2‐ethanediol with a chiral non‐racemic amine gave diastereomeric ligands bearing achirotopic stereogenic phosphorus atoms which were characterized with the assistance of X‐ray crystallography and variable temperature NMR studies. This work provides a new set of ligands that may be useful in some asymmetric reactions when phosphoramidites based on BINOL and TADDOL are ineffective. We also identify a novel stereochemical feature of phosphoramidites that may be useful in asymmetric catalysis and ligand design.