Phosphoramidite ligands based on simple 1,2-diols: Synthesis, use in Cu-catalyzed asymmetric additions, and achirotopic stereogenic phosphorus centers

Journal article

Phosphoramidite ligands are widely used in catalysis and normally constructed from large C2-symmetric diols such as BINOL or TADDOL. We report 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 VT 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.

Authors: Fletcher, S; Mistry, N

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Advanced Synthesis and Catalysis
• Volume: 358
• Issue: 15
• Pages: 2489–2496
• Publication date: 2016-07-12
• Acceptance date: 2016-06-21
• DOI: 10.1002/adsc.201600368
• EISSN: 1615-4169
• ISSN: 1615-4150
• Keywords: phosphorus stereochemistry; ligands; asymmetric catalysis; achirotopic stereogenic; Phosphoramidite; copper catalysis