作者:G. Bringmann、O. Schupp、K. Peters、L. Walz、H.G. von Schnering
DOI:10.1016/0022-328x(92)88011-7
日期:1992.10
The preparation is reported of the first series of (racemic) chiral rhenium complexes with "axially prostereogenic" biaryl lactone ligands, which are potential substrates for atropisomer-selective biaryl syntheses. NMR spectroscopy reveals the presence of both helimeric forms of the twisted biaryllactone ligand for the more hindered representatives (R = Me, Et), whereas the less hindered compounds (R = H, OMe) show rapid interconversion of the two helimeric diastereomers. In the crystal, by contrast, one of the complexes (R = OMe) occurs as only one of the two possible diastereomers, as shown by an X-ray diffraction study.