Dioxane derivatives

Details Dioxane derivatives Dioxane derivatives

1995-03-01

1997-11-04

Kelly, C. H.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

549369, 549370, C09K 1934, C07D31906, C07D40700

Patent

active

056836236

DESCRIPTION:

BRIEF SUMMARY
This application is a continuation of 371 application PCT GB 93/01929
This invention relates to dioxane derivatives which are useful as components in liquid crystal compositions. Such compositions may be incorporated in liquid crystal devices (LCD) and exhibit useful electro-optical effects. The invention also relates to such compositions and to the LCDs incorporating them. In particular it relates to those compositions which exhibit ferroelectric behaviour and allow the LCDs containing them to have very fast switching speed, bi-stable characteristics, enhanced greyscale and storage capabilities and wide viewing angle.
Accordingly we provide a compound of the formula A: ##STR2## Wherein X is CH or B R.sup.1, R.sup.2, are each A.sup.1, OA.sup.1, OCOA.sup.2, or COOA.sup.2 carbon atoms and may be substituted with one or more F or CN. containing from 5 to 10 carbon atoms and may be substituted with one or more F or CN and if straight may be unsubstituted. OCO(CH.sub.2).sub.p either or both of Z.sub.1 and Z.sub.2 are F and, when not F, are H ##STR3##
Particularly useful compounds are those wherein A.sup.2 is an optically active branched chain alkyl group substituted by a single F or CN.
Individual compounds which have been found to be particularly useful include the following. A), B), C), D), E), F), (compound G), (compound H)


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a compound production scheme according to the invention.
FIG. 2 is another illustration of a compound production scheme.
FIG. 3 is another illustration of a compound production scheme.
FIG. 4 is another illustration of a compound production scheme.
The compounds of this invention may be synthesised by the following methods. ##STR4## i.e. wherein, in general formula A, X is CH;
These compounds are produced according to the scheme illustrated in FIG. 1. In this scheme diethyl malonate (formula 1) is reacted with the compound R.sup.1 Br in sodium ethoxide/ethanol to give the R.sup.1 -substituted diethyl malonate of formula 2. Reduction of this with lithium aluminium hydride in ether yields the corresponding diol (formula 3) which is then reacted with 4-bromobenzaldehyde and 4-toluene sulphonic acid in dry toluene to give the compound of formula 4. Reaction of 1,2-difluorobenzene (formula 5) with the compound containing from 1 to 18 carbon atoms, optionally substituted with one or more F or CN, with n-butyllithium in tetrahydrofuran followed by treatment with phosphorous pentoxide in light petrol and then by reduction over palladium charcoal yields the compound of formula 6. Treatment of this compound with n-butyllithium in tetrahydrofuran followed by triisopropyl borate gives the compound of formula 7. Finally the compounds of formulae 4 and 7 are reacted in the presence of tetrakis(triphenylphosphine) palladium and aqueous sodium carbonate to yield the required compound of formula 11. ##STR5## i.e. wherein, in general formula A, X is CH;
Referring again to the scheme illustrated in FIG. 1, reaction of 2,3-difluorophenol (formula 8) with the compound R2Br over potassium carbonate in acetone gives the 2,3-difluorophenyl compound of formula 9 which on reaction with firstly butyl lithium under nitrogen at -78.degree. C. and then with tri-isopropyl borate gives the compound of formula 10. The compounds of formulae 4 and 10 are then reacted in the presence of tetrakis(triphenylphosphine) palladium and aqueous sodium carbonate to yield the required compound of formula 12. ##STR6## i.e. wherein, in general formula A, X is CH;
These compounds are produced according to the scheme illustrated in FIG. 2. In this scheme, the compound of formula 4 (see FIG. 1 and description above), after reaction with n-butyllithium in THF under nitrogen, is poured onto carbon dioxide granules giving the 4-substituted benzoic acid of formula 13. The compound of formula 7 (see also FIG. 1) is converted to the corresponding phenol of formula 14 by reaction with hydrogen peroxide in ether. The compounds of formulae 13 and 14 are then reacted with N,N'-dicycl

REFERENCES:
patent: 4344856 (1982-08-01), Demus et al.
patent: 4348324 (1982-09-01), Demus et al.
patent: 4450094 (1984-05-01), Sato et al.
patent: 4486332 (1984-12-01), Demus et al.
patent: 4853150 (1989-08-01), Bezaborodov et al.
patent: 5171471 (1992-12-01), Suzuki et al.
patent: 5254698 (1993-10-01), Coates et al.
Mol. Cryst Lig Crsy, 1991, vol. 221 pp. 161-164.

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