Process for preparing silacyclohexane-base liquid crystal compounds

A process for preparing another type of silacyclohexaneo-based liquid crystal compound of the following formula (II) ##STR31## wherein R represents a phenyl group, a tolyl group, a linear alkyl group having from 1 to 10 carbon atoms, a mono or difluoroalkyl group having from 1 to 10 carbon atoms, a branched alkyl group having from 3 to 8 carbon atoms or an alkoxyalkyl group having from 2 to 7 carbon atoms, Y represents a halogen or CH.sub.3, and i is a value of 0, 1, 2 or 3, and X represents R or OR, wherein R has the same meaning as defined above, CN, F, Cl, Br, CF.sub.3, OCF.sub.3, OCHF.sub.2, OCHFCl, OCF.sub.2 Cl, CF.sub.2 Cl, --(O).sub.m --C Y.sub.1 =CX.sub.1 X.sub.2 wherein m is a value of 0 or 1, Y.sub.1 and X.sub.1, respectively, represent H, F or Cl, and X.sub.2 represents F or Cl, or --O--(CH.sub.2).sub.r (CF.sub.2).sub.s X.sub.3 wherein r and s are, respectively, a value of 0, 1 or 2 provided that r+s=2, 3 or 4, and X.sub.3 represents H, F or Cl, the process comprising the steps of:

• (1) subjecting a ketone compound of the following formula ##STR32## Ar represents a phenyl group or a tolyl group, R has the same meaning as defined above, to reaction with an organometal reagent of the following formula ##STR33## wherein M represents Li, MgU, ZnU or TiU.sub.k (OW).sub.3-k in which U represents a halogen, W represents an alkyl group, and k is zero or an integer of 1 to 3, Y, i and X have, respectively, the same meanings as defined above to obtain a compound of the following formula ##STR34## (2) subjecting the thus obtained compound of the above formula to dehydration and then to oxidation to obtain a compound of the following formula ##STR35## (3) subjecting the thus obtained compound of the above formula to de-silylation and then to reduction to obtain the silacyclohexane-based compound of the formula (II) defined above.

A process for preparing a silacyclohexane-based liquid crystal compound of the following formula (III) ##STR36## wherein R represents a phenyl group, a tolyl group, a linear alkyl group having from 1 to 10 carbon atoms, a mono or difluoroalkyl group having from 1 to 10 carbon atoms, a branched alkyl group having from 3 to 8 carbon atoms or an alkoxyalkyl group having from 2 to 7 carbon atoms, Y represents a halogen or CH.sub.3, and i is a value of 0, 1, 2 or 3, and X represents R or OR, wherein R has the same meaning as defined above, CN, F, Cl, Br, CF.sub.3, OCF.sub.3, OCHF.sub.2, OCHFCl, OCF.sub.2 Cl, CF.sub.2 Cl, --(O).sub.m --C Y.sub.1 =CX.sub.1 X.sub.2 wherein m is a value of 0 or 1, Y.sub.1 and X.sub.1, respectively, represent H, F or Cl, and X.sub.2 represents F or Cl, or --O--(CH.sub.2).sub.r (CF.sub.2).sub.s X.sub.3 wherein r and s are, respectively, a value of 0, 1 or 2 provided that r+s=2, 3 or 4, and X.sub.3 represents H, F or Cl, Z represents a halogen or CH.sub.3, and j is a value of 0, 1, 2 or 3, the process comprising the steps of:

• (1) subjecting a ketone compound of the following formula ##STR37## Ar represents a phenyl group or a tolyl group, R has the same meaning as defined above, to reaction with an organometal reagent of the following formula ##STR38## wherein M represents Li, MgU, ZnU or TiU.sub.k (OW).sub.3-k in which U represents a halogen, W represents an alkyl group atoms, and k is zero or an integer of 1 to 3, Y, Z, i, j and X have, respectively, the same meanings as defined above to obtain a compound of the following formula ##STR39## (2) subjecting the compound of the formula (9) to dehydration and then to oxidation, to obtain a compound of the following formula ##STR40## (3) subjecting the thus obtained compound of the above formula to de-silylation and then to reduction to obtain the silacyclohexane-based compound of the formula (III) defined above.