Neuartige discotisch-flüssigkristalline, polare Monothioscyllitol-Derivate [1,2] / Novel Discotic Liquid Crystalline, Polar Monothioscyllitol Derivatives [1,2]

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Abstract
3-5: On the basis of an improved synthesis of the 1,3,4,5,6-pentaacetate of myo-inositol, now available in only one step from that cyclitol in yields up to 90%, we prepared various derivatives of 1-deoxy-1-mercapto-scyllo-inositol (monothioscyllitol) via the mesylate 1 a or the trifluoromesylate 1 b , respectively. The non-centrosymmtric disc-shaped thioethers 3a-h as well as their S,S-dioxides 4a-h and the S-oxide 5f exhibit thermotropic discotic mesophases over wide temperature ranges. The thermomesomorphism of these new sulfur compounds has been studied by optical microscopy and by differential scanning calorimetry. The pentabutyrates 3a and 4a as well as the dimesomorphic pentapentanoate 3 b exhibit a probably new type of discophase Dx whereas all other monothioscyllitol derivatives with longer alkyl chains show the Dho-phase over wide temperature ranges. Of some selected new thioethers 3, sulfones 4, and of the sulfoxide 5f the dipole moments have been measured which are highest with the cyano derivatives 3g and 4g at about 5 or above 6 D, respectively. These values characterize them as the strongest polar discogens studied so far. The presented monothioscyllitol derivatives 3, 4 and 5 do not only increase the number of rarely known polar discogens, but also show that non-centrosymmetric and polar discotic liquid crystals with a small, alimonocyclic, saturated "core" now can be prepared easily. Their permanent electric dipole moments could give rise to interesting magnetic or electric field effects.

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