We report the synthesis of a novel class of planar chiral bidentate aryl[2.2]paracyclophane ligands. For the first time in the [2.2]paracyclophanyl series the Pd-catalyzed Suzuki cross-coupling was employed for the formation of the arylparacyclophanyl skeleton. From the two possible approaches: (a) cross-coupling of [2.2]paracyalophanylboronic acids with aryl halides; (b) cross-coupling of [2.2]paracyclophanyl
Synthesis of novel planar-chiral [2.2]paracyclophane derivatives as potential ligands for asymmetric catalysis
作者:Michael Kreis、Martin Nieger、Stefan Bräse
DOI:10.1016/j.jorganchem.2005.10.031
日期:2006.5
The synthesis of a variety of new 4,5-disubstituted [2.2]paracyclophane derivatives has been achieved employing different cross-coupling reactions. By this methodology, a heteroatom-variation of successful catalyst ligands was achieved, giving rise to a modular ligand system. The X-ray structure of 4-hydroxy-5-(1′-hydroxy-1′-phenylethyl)-[2.2]paracyclophane was determined to elucidate the configuration
Development of a New Dimeric Cyclophane Ligand: Application to Enhanced Diastereo- and Enantioselectivity in the Catalytic Synthesis of β-Lactams
作者:Harald Wack、Stefan France、Ahmed M. Hafez、William J. Drury、Anthony Weatherwax、Thomas Lectka
DOI:10.1021/jo049804d
日期:2004.6.1
We detail the synthesis of a new C2-symmetric bis(cyclophane) ligand system that can be thought of as electronically analogous to binol, but which possesses the added “third dimension” of cyclophane chirality. The ligand synthesis involves a spontaneous (but unexpected) atropisomerization to the desired product. We have employed this ligand to form a metal complex that is an effective cocatalyst for