New (1R,4R)-2-arylidene-p-menthan-3-ones with a bridging ester group in the arylidene fragment. Synthesis and behavior in liquid-crystalline systems
作者:V. V. Vashchenko、L. A. Kutulya、M. N. Pivnenko、N. I. Shkolnikova
DOI:10.1023/b:rucb.0000012363.37580.30
日期:2003.11
(1R,4R)-2-(4-Hydroxybenzylidene)- and (1R,4R)-2-(4'-hydroxybiphenyl-4-yl)methylene-p-menthan-3-ones were synthesized by condensation of (-)-menthone with O-tetrahydropyran-2-yl derivatives of 4-hydroxybenzaldehyde and 4'-hydroxy-4-formylbiphenyl, respectively, in a DMSO-base medium followed by the removal of the protective group. The reactions of these hydroxy derivatives with 4-alkylbenzoic, 4-alkyloxybenzoic, traps-4-alkylcyclohexane-4-carboxylic, and 4'-alkylbiphenyl-4-carboxylic acids afforded three series of new chiral esters. Compounds containing the arylidene moiety with three benzene rings were found to exhibit liquid-crystalline properties. The characteristic features of these compounds are discussed based on the results of studies by polarizing microscopy, differential scanning calorimetry, and small-angle X-ray scattering. It was found that the mesomorphic compounds under study can form a smectic A mesophase, twist grain boundary mesophases (TGBA), and blue phases in a wide temperature range. Upon dissolution of certain of chiral compounds in 4'-cyano-4-pentylbiphenyl, a rather high twisting power and the thermal stabilizing effect on mesophases were observed.
(1R,4R)-2-(4-羟基苯甲基)-和(1R,4R)-2-(4'-羟基二苯基-4-基)甲基-p-薄荷烷-3-酮是通过(-)-薄荷酮与4-羟基苯甲醛和4'-羟基-4-甲酰二苯基的O-四氢吡喃-2-基衍生物在DMSO基介质中缩合,随后去除保护基团而合成的。这些酚衍生物与4-烷基苯甲酸、4-烷氧基苯甲酸、陷阱-4-烷基环己烷-4-羧酸以及4'-烷基二苯基-4-羧酸的反应生成了三类新的手性酯。含有三苯环肉桂基结构的这些衍生物被发现具有液晶性质。基于偏光显微镜、差示扫描量热法和小角X射线散射法的研究结果,讨论了这些化合物的特征。发现研究中的介晶化合物可以在较宽的温度范围内形成一个层状A介晶相、扭曲晶界介晶相(TGBA)以及蓝相。当某些手性化合物溶解于4'-氰基-4-戊基二苯基中时,观察到较高的扭曲力和对介晶相的热稳定效应。