Synthesis of 2-(alkanoyloxy)-5-alkoxytropones. Novel monocyclic rod-type liquid crystals

Mesomorphic property of 2,5-dibenzoyloxy-, 5-benzoylamino-2-benzoyloxy-, and 2,5-dibenzoylamino-tropones with mono-, di-, and tri-alkoxyl groups on the benzoyl groups and their benzenoid derivatives

“…These behaviours are explained by the migration of the benzoyl group at the C-2 position between the oxygen atom and the tropone carbonyl group, so-called [1,9]-sigmatropy [7]. Other troponoids (1,2,(4)(5)(6) with a benzoyloxy group at the C-2 position behaved similarly.…”

“…The corresponding benzenoids were similarly synthesised (Scheme 2). The nuclear magnetic resonance (NMR) spectra of troponoids 1-6 with a benzoyloxy group at the C-2 position are characteristic as observed in 2-acyloxytropones [8][9][10][11][12]. The patterns of the NMR spectra are largely dependent on the measuring temperature.…”

“…In this paper, we synthesise 2,5-dibenzoyloxytropones (1)(2)(3), 5-benzoylamino-2-benzoyloxytropones (4)(5)(6), and 2,5-dibenzoylaminotropones (7)(8)(9) with mono-, di-, and tri-alkoxy groups on the benzoyl group and the corresponding benzenoids (10)(11)(12)(13)(14)(15)(16)(17)(18) to discuss the difference in mesomorphic properties depending on the core structures as well as the connecting groups.…”

Monocyclic rod-type liquid crystals; 2,5-dialkanoyloxytropones and 5-alkanoyloxy-2-alkoxytropones

“…4-(4-alkoxybenzylidene)aminobenzoic acids [3]. They Previously, we have reported that monocyclic pointed out that the tropolone ring decreased the 2-alkanoyloxy-5-alkoxytropones (1) show a monotropic stability of the mesophase due to the larger molecular smectic A (SmA) phase [6]. We proposed that the width of the seven-membered ring (6.4 A Ê ) compared with mesogenic properties of the compounds 1 would be induced by the migration of an acyl group ( [1,9] sigmatropic rearrangement) between the two oxygen (5) in order to compare their mesogenic properties with those of compounds 1 [7].…”

“…The organic layer and ethyl acetate (3 : 1) on a silica gel column. The product was recrystallized with methanol to give colourwas evaporated in vacuo to leave a residue which was chromatographed in benzene on a silica gel column to less crystals (4o, 214 mg, 44% 2,5-dialkanoyloxytropones (4) with diOE erent alkyl chain lengths were prepared in 28-89% yield by the reaction (2H, m), 1.91 (2H, m), 2.53 (2H, t, J 5 6.8 Hz), 4.03 (2H, t, J 5 6.8 Hz), 6.63 (1H, d, J 5 11.0 Hz), 6.76 (1H, dd, of 6 with a molar equivalent of alkanoyl chloride to give 5-alkanoyloxytropolones (7), which were further reacted J 5 11.0, 2.6 Hz), 6 …”