Optically Active (aR)- and (aS)-Linear and Vaulted Biaryl Ligands: Deracemization versus Oxidative Dimerization
摘要:
The copper-mediated deracemization of the C2-symmetric vaulted biaryl ligands VANOL and VAPOL has been investigated. In the course of the studies that have led to a more reliable procedure for this process, an unprecedented oxidative dimerization of these ligands has been uncovered. The structures of these oxidative dimerization products were elucidated by a series of NMR experiments, and these assignments were supported by other spectroscopic techniques as well as their chemical reactivity. This oxidative dimerization process was not observed for the linear biaryl ligands BANOL and BINOL, although the new deracemization procedure was effective for the generation of BINOL with high optical purity. The (aS)-enantiomers of BINOL, VANOL and VAPOL were accessible with a copper complex of (-)-sparteine, and the (aR)-enantiomeric series were accessible with a copper complex of O'Brien's diamine. Both sparteine and O'Brien's diamine give higher optical purities with VANOL and VAPOL than with BINOL, and this is consistent with the steric congestion present in the matched and mismatched copper complexes of these diamines with the biaryl ligands.
2,2'-Binaphthalene Ester Chiral Dopants for Cholesteric Liquid Crystal Displays
申请人:Diehl Donald R.
公开号:US20140054498A1
公开(公告)日:2014-02-27
A liquid crystal composition comprising a chiral dopant compound represented by the following structure (Structure 1):
wherein:
R1 and R2 are independently hydrogen, —(C═O)R9, —(C═O)R10, alkyl, aryl, alkaryl, alkenyl, cycloalkyl, alkoxyaryl, or heterocyclic all either substituted or unsubstituted, or combine to form a carbocyclic or heterocyclic ring; and R3-R9 are as described in the disclosure.
Also featured are liquid crystal compositions comprising a chiral dopant compound represented by any of Structure 2-4 as described in the disclosure.
Optically Active (<i>aR</i>)- and (<i>aS</i>)-Linear and Vaulted Biaryl Ligands: Deracemization versus Oxidative Dimerization
作者:Gang Hu、Daniel Holmes、Brina Fay Gendhar、William D. Wulff
DOI:10.1021/ja903820m
日期:2009.10.14
The copper-mediated deracemization of the C2-symmetric vaulted biaryl ligands VANOL and VAPOL has been investigated. In the course of the studies that have led to a more reliable procedure for this process, an unprecedented oxidative dimerization of these ligands has been uncovered. The structures of these oxidative dimerization products were elucidated by a series of NMR experiments, and these assignments were supported by other spectroscopic techniques as well as their chemical reactivity. This oxidative dimerization process was not observed for the linear biaryl ligands BANOL and BINOL, although the new deracemization procedure was effective for the generation of BINOL with high optical purity. The (aS)-enantiomers of BINOL, VANOL and VAPOL were accessible with a copper complex of (-)-sparteine, and the (aR)-enantiomeric series were accessible with a copper complex of O'Brien's diamine. Both sparteine and O'Brien's diamine give higher optical purities with VANOL and VAPOL than with BINOL, and this is consistent with the steric congestion present in the matched and mismatched copper complexes of these diamines with the biaryl ligands.
New Derivatives of VAPOL and VANOL: Structurally Distinct Vaulted Chiral Ligands and Brønsted Acid Catalysts
作者:William Wulff、Aman Desai
DOI:10.1055/s-0030-1258231
日期:2010.11
Lean and efficient multi-gram scale syntheses of a number of new derivatives of VAPOL and VANOL are described. These are structurally novel chiral ligands and Brønstedacid catalysts, and could provide singular profiles for reactivity and asymmetric inductions in catalysis. VAPOL - VANOL - ligand - Brønstedacid - asymmetric catalysis