Substitution of Hydroxybiaryls via Directed <i>o</i><i>rtho</i>-Lithiation of <i>N</i>-Silylated <i>O</i>-Aryl <i>N</i>-Isopropylcarbamates
作者:Matthias Kauch、Victor Snieckus、Dieter Hoppe
DOI:10.1021/jo0506938
日期:2005.9.1
Herein we report regioselective substitution reactions of a series of 2- and 3-hydroxybiaryls including BINOL via a new directed ortho-metalation procedure. O-Aryl N-isopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, are temporarily and in situ N-protected by means of silyl triflates to form stable intermediates for low temperature lithiation reactions using butyllithium/TMEDA
3,3‘-Oxazolidinyl-Substituted 2,2‘-Biphenyldiols: Novel Tropos Ligands with a Large Induction on the Chiral Axis
作者:Stefan Wünnemann、Roland Fröhlich、Dieter Hoppe
DOI:10.1021/ol060528u
日期:2006.6.1
A novel type of bisphenol ligand is presented which provides high modularity. Chiral information is introduced in the 3,3 '-positions as N-arenesulfonyl-1,3-oxazolidines inducing an unexpectedly high diastereoselectivity of up to 98: 2 onto the chiral axis. The impact of each part of the molecule on the diastereomeric ratio is evaluated with extended variable-temperature (VT) NMR studies. A first example of application in asymmetric catalysis is given.
Oxidation of BINOLs by Hypervalent Iodine Reagents: Facile Synthesis of Xanthenes and Lactones
作者:Huaiyuan Zhang、Thomas Wirth
DOI:10.1002/chem.202200181
日期:2022.4.12
compounds. Binaphthyl-based xanthene derivatives were prepared through the oxidation of BINOLs promoted by the hypervalentiodinereagent iodosylbenzene (PhIO). Nine-membered lactones were obtained through a similar oxidative reaction when iodoxybenzene (PhIO2 ) was used. Additionally, one-pot reactions of BINOLs, PhIO and nucleophiles such as alcohols and amines were also investigated to provide alkoxylated