2-Amino-1,2,2-triphenylethanol: A Novel Chiral Reagent Containing the Diphenylaminomethyl Group. Enantioselective Addition of Diethylzinc to Benzaldehyde
2-Amino-1,2,2-triphenylethanol: A Novel Chiral Reagent Containing the Diphenylaminomethyl Group. Enantioselective Addition of Diethylzinc to Benzaldehyde
Both enantiomers of the novel amino alcohol (R)- and (S)-2 are prepared from the corresponding enantiomer of the mandelic acid-derived ethanediol 3. The regioisomeric amino alcohols 1 and 2 are converted into the imines 7 and 8, respectively. Titanium complexes 9 and 10 derived therefrom are used as catalysts for the addition of diethylzinc to benzaldehyde and yield the alcohol 11 in up to 92% ee.
Use of chiral, uncharged metal compounds as dopants for liquid-crystalline materials
申请人:BASF AKTIENGESELLSCHAFT
公开号:US20030066984A1
公开(公告)日:2003-04-10
Improved liquid crystalline materials may be prepared by doping liquid crystalline materials with chiral, uncharged metal compounds of formula [(P
1
—Y
1
—A
1
—Y
2
—M
1
—Y
3
—)
n
L]
2
Me or [(P
1
—Y
1
—A
1
—Y
2
—M
1
—Y
3
—)
n
L]Me(L′(—Y
6
—M
2
—Y
5
—A
2
—Y
4
—P
2
)
n′
)
m
. Groups P
1
and P
2
may be, independently, hydrogen, C
1
-C
12
-alkyl groups, polymerizable groups, or radicals containing a polymerizable group. Y
1
to Y
6
may be, independently, single chemical bonds, ether groups, thio groups, carbonyl groups, acid groups, etc. Groups A
1
and A
2
are spacers having from 1 to 30 carbon atoms, and M
1
and M
2
are mesogenic groups. Me may be a transition metal from the fourth, fifth or sixth period of the periodic table, except for technetium, silver, cadmium, gold, mercury, or any of the lanthanoids, or Me may be a main group element from group 14 (IUPAC system), except for carbon and lead. L is a tridentate ligand, and L′ is an organic group having up to 12 carbon atoms.
Reactions on (R) and (S)-1,1,2-triphenyl-1,2-ethandiols induced by aminium salts and protic acids. Solvent effect
作者:Luigi Lopez、Gianluca M. Farinola、Vincenza Paradiso、Giuseppe Mele、Angelo Nacci
DOI:10.1016/s0040-4020(97)00689-3
日期:1997.8
(R) and (S) 1,1,2-triphenyl-1,2-ethandiols (1a) and (1b), upon treatment of their dichloromethane solutions with catalytic amounts of aminium salt cation radicals afforded mixtures of the corresponding pinacolones (Ph3CCHO, 90 %) (2), (Ph2CHCOPh, 10%) (3), whereas similar reactions, carried out in acetonitrile, led to consistent amounts of both pinacolones, together with benzophenone (4), benzaldehyde (5) (minor amounts), and new products (30 %), fully characterized as (R) and (S) 4,4,5-triphenyl-2-methyloxazolines (7a,b). The formation of these latter was selectively inhibited in the aminium salt induced reactions, modified by 2,6-di-tert-butylpyridine (DBP). (C) 1997 Published by Elsevier Science Ltd.
Verwendung von chiralen, ungeladenen Metallverbindungen als Dotierstoffe für flüssigkristalline Materialien