‘Aromatic ring umpolung’, a rapid access to the main core of several natural products
作者:Kimiaka C. Guérard、Cyrille Sabot、Marc-André Beaulieu、Marc-André Giroux、Sylvain Canesi
DOI:10.1016/j.tet.2010.03.096
日期:2010.7
substituted phenols in the presence of (diacetoxyiodo)benzene promotes the formation of a phenoxenium ion, a very electrophilic species able to react with various nucleophiles leading rapidly to a plethora of different cores present in natural products via several novel oxidative processes. This strategy fits within the concept of ‘aromatic ring umpolung’; in this paper a personal account by our laboratory
An oxidative allylation process mediated by a hypervalent iodine reagent has been performed on polysubstituted phenols. This reaction, occurring in useful to good yields, leads to a rapid access to dienones containing a quaternary carbon center.
LIQUID-CRYSTALLINE MEDIUM AND LIQUID-CRYSTAL DISPLAY COMPRISING THE SAME AND COMPOUNDS
申请人:Merck Patent GmbH
公开号:US20210207029A1
公开(公告)日:2021-07-08
A liquid-crystalline medium having a nematic phase containing one or more compounds of formula D
the use thereof in an electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect, displays of this type which contain a liquid-crystalline medium of this type and the use of the compounds of formula D for improvement of the contrast and/or response times of a liquid-crystalline medium which contain one or more additional mesogenic compounds, as well as certain compounds of formula D.
Compounds of the formula I, and liquid-crystalline media, preferably having a nematic phase and negative dielectric anisotropy, comprising
a) one or more compounds of the formula I
and one or more compounds selected from
b) one or more compounds of formula II
and/or
c) one or more compounds selected from compounds of formulae III-1 to III-4 and formula B
Methods for making and using these liquid-crystalline media in electro-optical displays, particularly in active-matrix displays based on the VA, ECB, PALC, FFS or IPS effect and the displays which contain these media. Methods for stabilizing liquid-crystalline media with compounds of formula I, where the liquid-crystalline media comprise one or more compounds of the formula II and one or more compounds selected from compounds of the formulae III-1 to III-4 and formula B.
The present invention relates to a compound of the general formula I
in which the occurring groups and parameters have the meanings indicated in claim
1
, to the use thereof in liquid-crystalline or mesogenic media and to liquid-crystalline or mesogenic media comprising these derivatives.