The azulene ring as a structural element in liquid crystals Sia�n E. Estdale, Roger Brettle, David A. Dunmur and Charles M. Marson Department of Chemistry, University of Sheffield, Sheffield, UK S3 7HF A new approach to the synthesis of azulene liquid crystals is described based on Hafner’s procedure involving reaction of a pyridinium salt with a cyclopentadienide. The preparation of a variety of liquid crystalline materials using this method is described.Variants are reported with single substituents on the azulene ring in the 6-position and doubly substituted in the 2, 6- positions. The effect of the azulene ring as a core or dipolar terminal structural element is explored. 6-(5-Alkyl-1,3-dioxan-2- yl)azulenes are shown to exhibit smectic A phases and 2-cyclohexyl-6-(5-tridecyl-1,3-dioxan-2-yl)azulene show smectic A and B phases.Phase characterisation of the materials is recorded together with X-ray measurements on the smectic A phase of one representative compound. Results of dichroism studies on the azulene mesogens are also briefly reviewed. The essential structure of a calamitic mesogen incorporates a Simple alkyl propane-1,3-diols were prepared by reacting rigid core with a flexible terminal chain, and often a polar end diethyl malonate with the appropriate alkyl halide and then group, and mesophase behaviour is strongly dependent on the reducing the ester groups with LiAlH4; 2-(4-alkyloxyphenyl)- nature of the core.In the search for new mesogenic structures, propane-1,3-diols were prepared by reacting ethyl 4-alkoxythe azulene ring system potentially opens up a whole new phenylacetates with diethyl oxalate; the product was then range of liquid crystal types.The azulene ring C10H10 is a non- decarbonylated and reduced with LiAlH4. benzenoid aromatic hydrocarbon with an intrinsic dipole The products derived from Scheme 1 were a mixture of cis moment (1.08 D) which is delocalised over the whole ring.1 and trans isomers which were separable by MPLC or HPLC, Azulenes are chromophores: the deep blue colour of the parent and were assigned by the characteristic 1H NMR spectra for compound arises from the electronic transitionfrom the highest the two CH2 groups on the dioxan-2-yl ring.For the cis- occupied molecular orbital to the lowest unoccupied antibond- isomers, the chemical shift difference between the axial and ing orbital (the 1Lb band).2 The azulene ring system is planar equatorial hydrogens is small whereas a large chemical shift and thermodynamically stable, although the 10p electrons difference is observed for the trans isomers and this character- display the reactivity expected of an aromatic system.istic pattern agrees with previously published results.12 Substitution of the ring can alter the wavelength of this absorption band resulting in different colours for different azulene derivatives.Praefcke and Schmidt3 reported the synthesis of substituted azulenes linked to nematogenic alkylcyclohexanes by an ester group following the Nozoe procedure.4 We have also used this Attempts were also made to prepare mesogenic azulenes route to produce mesogenic azulenes5 with alkylbiphenyls as with a phenyl ring instead of the dioxan-2-yl ring.Two the mesogenic moiety. In 1990, a series of patents by Mitsubishi homologues 2a,b were prepared by different methods. described the synthesis of a range of 2-substituted,6 6-substi- Deprotection of 1a with dilute hydrochloric acid gives azulene- tuted7 and 2,6-disubstituted azulenes8–10 using the Nozoe route, 6-carbaldehyde which was reacted with the appropriate some of which were mesogenic.Only limited data were pre- Wadsworth–Emmons reagent to give 6-(4-hexyloxystryryl)- sented on the mesophase behaviour of these compounds which azulene, which rapidly decomposed. Reduction of the double were mostly examined as solutes in a nematic host material.bond gave 2a. The C10 analogue, 2b was prepared by reducing The mesophase properties of previously reported azulene based the double bond of the appropriate stilbazole, quaternising the liquid crystals are summarised in Table 1. product with 1-bromobutane and reacting the resulting pyridinium salt with sodium cyclopentadienide. Synthesis In order to prepare potentially mesogenic azulenes without ester linkages, we adopted the Hafner synthesis11 where an N- Mesophase Behaviour alkyl-4-methylpyridinium salt was reacted with sodium cyclo- Of the compounds synthesised, the trans isomers of 1e–k, 1n pentadienide to give 6-methylazulene (see Schemes 1 and 2).and 1p were mesogenic. Table 2 shows the transition tempera- In a similar way we prepared 6-(diethoxymethyl)azulene 1a tures for compounds 1e–k which showed a monotropic smectic by reaction of sodium cyclopentadienide with 4-(diethoxy- A phase.These trans isomers exhibited two crystal forms (K1 methyl)pyridinium bromide. Alternatively, reaction with and K2) which melted at different temperatures. The observed monosubstituted sodium cyclopentadienides gave a mixture of phase sequence is shown in Fig. 1 and illustrates the trends in 1,6- and 2,6-disubstituted azulenes which, in some cases, were melting points of the two crystal forms and the SA phase. (For separable by HPLC. Transacetalation of the diethoxymethyl the two metastable crystal states:K1 corresponds to the melting group with 2-substituted propane-1,3-diols then gave substituted azulenes, some of which were mesogenic.point on initially heating the crystal from room temperature, J. Mater. Chem., 1997, 7(3), 391–401 391Table 1 Transition temperatures and wavelengths of visible absorption of mesogenic azulenes previously reported in the literature transition tempa/°C R1 R2 R3 R4 lmax/nm K N I ref. H CO2Et CO2Et $ 136 $ (110.5) $ 3 H CO2Me CO2Me $ 149 $ (121.9) $ 3 H CO2Et CO2Et 480 $ 123.7 $ (115.9) $ 3 H CO2Pr CO2Pr $ 104.5 $ (89.3) $ 3 H CO2Et H 510 $ 86.1 $ 153.2 $ 3 H CO2Et CO2Et $ 144 $ (78.6) $ 5 H CO2Et H $ 146 $ (145) $ 5 CO2Et CO2Et 475 $ 122 $ (111) $ 8 H H H 476 $ 118 $ (122.6) $ 7 H H H 566 $ 106.7 $ 119.4 $ 7 aParentheses indicate a monotropic transition. and K2 is the melting point when heating the crystal phase calculated to be 27 A° .Molecular modelling calculations were then made in an attempt to describe the molecular arrange- formed on cooling). For compounds where K2 is lower than the monotropic smectic A transition temperature an enanti- ment. At 0 K, the molecular length was determined from MACROMODELto be 27.56 A°, which is close to the observed otropic SA phase is observed.The trans isomer of 1n showed a crystal B phase at around value for the inter-layer spacing of this smectic A phase. An even closer value is obtained when part of the molecule is 170 °C and was identified by the lancet texture observed on cooling from the isotropic phase. For compound 1p, where the tilted with respect to the smectic layers; this has the effect of shorteningthe apparent length of the molecule and calculations 2-substituent is an unsubstituted cyclohexyl ring, smectic A (144 °C) and smectic hexatic B (117°C) phases were observed.predict a value of 26.9 A° at 300 K. However, modelling the molecule at 357 K, the value for the molecular length decreases Compound 1q was prepared as it was hoped that the molecular length could then be extended with a collinear chain on the to 23.65 A°.The entropy of the system is now greater, and this manifests itself in thermal agitation of the alkyl chain which is cyclohexyl ring; however the cis and trans isomers were inseparable by HPLC. no longer fully extended. From this result it is possible to rule out a monolayer structure for this SA phase, since for the Addition of a 2-cyclohexyl substituent (compound 1p) increases the thermal stability of the SA phase compared to temperatures at which the phase is observed, there will be some thermal agitation of the alkyl chain, and the measured the singly substituted 6-(tridecyl-1,3-dioxan-2-yl)azulene, 1h which showed a monotropic smectic A phase, such that an molecular length must be less than the calculated value with a fully extended chain.enantiotropic phase is now observed. This molecule inrporates an aromatic ring with saturated cyclic groups either side In considering how the molecules are arranged within the layers, the intermolecular interactions must also be considered. of it, which traditionally has been considered unfavourable for mesogenic behaviour. Potentially, this molecule opens up a Azulene has a distributed dipole moment and dipolar resonance forms of azulene will contribute to the intermolecular new series of mesogens and it is expected that the addition of a terminal alkyl chain on to the cyclohexyl ring will lower the interactions in the smectic mesophase. It has been reported in the literature13,14 that only anti-azulenophanes of the type clearing points and transition temperatures of the observed mesophases. shown (Fig. 2) can be formed, since this minimises the energy of both the resonance and electrostatic interactions between Small angle X-ray measurements were made for compound 1f, 6-(5-undecyl-1,3-dioxan-2-yl)azulene. From the data the interacting azulene pairs. For the corresponding synazulenophase these interactions would be repulsive.It is obtained, an average value for the inter-layer spacing was 392 J. Mater. Chem., 1997, 7(3), 391–401that involves extensive interdigitation of the alkyl chains, which accounts for both the dipolar interactions of the azulene ring and the thermal disorder of the alkyl chains. Linear Dichroism Since azulene derivatives are coloured, their use as dichroic materials in liquid crystal devices is of some interest.Measurement of the linear dichroism of a number of nonmesogenic and mesogenic compounds dissolved in suitable nematic host materials have been reported.16 Measurements were also carried out on three compounds prepared in this work. From these studies it is possible to determine the degree of order of the host azulene molecules and the angle made by the transition moment to the long molecular axis. For the parent azulene, the transition moment responsible for the characteristic blue colour is polarized perpendicular to the axis2 through carbon atoms 2 and 6.Substitution of the azulene ring and attachment of different terminal groups change the absorption frequency and the angle of the transition moment with respect to the molecular axis.Consequently, it is possible to make azulene liquid crystal mixtures having different colours and with either positive or negative linear dichroism. In Table 3 absorption frequencies and dichroic ratios are summarised for a range of azulene derivatives: a dichroic ratio of less than one indicates that the optical absorption perpendicular to the azulene molecular axis is larger than along the axis.Conclusions New 6-substituted azulenes were successfully synthesised by reacting functionalised N-alkylpyridinium salts with sodium cyclopentadienide to give mesogenic azulenes where the azulene ring was incorporated as an end group. The preparation of 6-(diethoxymethyl)azulene 1a and azulene-6-carbaldehyde was significant as they are functionalised azulenes which may be reacted further to give new 6-substituted azulene compounds.The development of the transacetalation reaction of 6-(diethoxymethyl)azulene led to a new homologous series of mesogenic azulenes which exhibited monotropic smectic A phases in the range 78 to 86°C. These compounds are the first reported azulenes to show a smectic phase. In these compounds it may be argued that the azulene ring has a dual role, and is behaving both as part of the core and as a polar end group.Scheme 1 Molecular modelling substantiated the claim that the dipolar interactions of adjacent azulene rings are important in determining the intermolecular interactions which results in the observed smectic A layered structure, with the alkyl chains extensively interdigitated. Attempts to extend the core led to the synthesis of 6-[5-(4- dodecyloxyphenyl)-1,3-dioxan-2-yl]azulene, 1n.A crystal B phase was observed in the range 170–190 °C. This contrasts with related compounds without a phenyl group as part of the core, which form a smectic A phase approximately 100 °C lower. It was also possible to prepare potential azulene mesogens by hydrogenation of a stilbazole and reacting the quarternised salt with sodium cyclopentadienide. Unfortunately, the resultant 6-(4-decyloxyphenethyl)azulene, 2b was not mesogenic, which can be attributed to the separation of the N H O N O O N O O OH OH Bu + O O Br– – Na+ 1b aromatic rings by a flexible dimethylene linkage.(However, Scheme 2 the intermediate 4-(4¾-decyloxyphenethyl)pyridine was mesogenic, and exhibited a smecticA phase in the range 159–222°C.) New 1,6- and 2,6-disubstituted azulenes were synthesised by expected that in the observed mesophase the azulene rings would adopt a packing arrangement which minimises the the reaction of functionalised N-alkylpyridinum salts with sodium monosubstituted cyclopentadienides.The synthesis of energy of these types of interactions, resulting in an antiparallel bilayer structure as illustrated (Fig. 3). A similar type 2-cyclohexyl-6-(tridecyl-1,3-dioxan-2-yl)azulene 1p gave a mesogen which showed a smectic A and a smectic B phase in of alignment is observed in mesogens with strongly polar groups.15 Our proposed structure for the SA phase is a bilayer the range 95–144 °C.All previously reported azulene mesogens J. Mater. Chem., 1997, 7(3), 391–401 393Table 2 Mesophase behaviour of azulene liquid crystals transition temperatures (microscopy) transition data (DSC) cis compound mp K1 mp/°C K2mp/°C (SA/I)/°C DH/kJ mol-1 Tonset/°C DS J K-1 mol-1 1c 81.4 100.1 — — 1d 83.6 99.6 — — 1e 94.5 94.5 76.8 83.9 4350 82 12.3 1f 96.9 97.8 — (84.1) 3350 79 9.5 1g 97.5 98.5 78.5 85.0 3440 79 9.8 1h 99.7 101.1 80.0 84.0 3150 79 9.0 1i 100.2 102.1 86.0 (83.9) 4210 80 11.9 1j 102.1 102.8 88.0 (79.5) 3290 77 9.4 1k 103.4 103.9 90.0 (78.9) 4000 75 11.5 are linked through ester groups.It is anticipated that substitution of the cyclohexyl ring by an alkyl chain will lead to a new homologous series with lower clearing points and transition temperatures.The linear dichroism of some azulene mesogens was determined by measuring the order parameter of these compounds as dyes in liquid crystal hosts. The optical order parameters were low as a result of the large angle which the transition moment makes with the molecular axis; in some cases this angle was close to the magic angle of 54°44¾ at which the dichroism is zero.As a result of the large angle, it was possible to vary the sign of the dichroism by varying the substituents on the azulene ring. However, these compounds are not suitable for use in guest–host displays despite the high extinction coefficients. Fig. 1 Phase diagram of compounds 1c –k: (a) K1–I; (1) SA–I; (p) Various aspects of the synthesis and physical properties of K2 – SA; (c) K2 –I azulene liquid crystals have been explored in this work.It is evident that the synthesis of azulene is difficult and having tried a number of routes, the most successful method for this work involved the reaction of N-alkylpyridinium salts with sodium cyclopentadienide. However, the development of new azulene based liquid crystals is restricted by the limited synthetic routes currently available.Experimental Fig. 2 Structures of the azuleneophanes Reactions sensitive to moisture and air were carried out in flame-dried glassware under nitrogen or argon using freshly distilled solvents. Solvents were dried and purified according to literature methods. Thin-layer chromatography on TLC aluminium sheets pre-coated with silica gel (Merck 69) F254 was used to monitor reactions and to establish the purity of samples.TLC plates were inspected using UV light or developed with iodine vapour. Oil-free sodium hydride was obtained by washing with dry light petroleum in an argon atmosphere. Amberlyst 15 (H+) ion-exchange resin was used in transacetalation reactions. Column chromatography separations were performed on silica gel (Merck 60) or neutral silica (Merck, 60) as the stationary phase.Loading of the sample was carried out either as a concentrated solution of the mixture in the solvent used for the mobile phase, or whenever the mixture was only sparingly soluble in the eluent, it was supported on silica gel by dissolving in a solvent, adding silica and evaporating the slurry to dryness to leave a powder which was poured on to the top of the column.Organic solutions were dried over magnesium sulfate unless otherwise stated. Melting points were determined using either a Reichert-Ko�fler hot-stage apparatus or a Zeiss-Labpol microscope equipped with crossed polarisers and a Linkam hot-stage with integrated temperature controller, and are uncorrected. Elemental analyses were performed by the University of Sheffield Microanalytical Service.Low resolution mass spectra were recorded using a Kratos MS 25 mass spectrometer. High resolution mass spectra was recorded using a Kratos MS 60 mass spectrometer to give Fig. 3 Proposed layer structure of the smectic A phase involving extensive interdigitation accurate mass values. 1H and 13C NMR spectra were recorded 394 J.Mater. Chem., 1997, 7(3), 391–401Table 3 Absorption frequencies and dichroic ratios for a range of azulene derivatives compound lmax/nm emax/cm2 mol-1 dichroic ratio AII/A) ref. 548 280000 1.0 17 565 340000 1.0 17 590 440000 1.44 17 480 720000 1.8a 3 510 630000 2.1a 3 468 560000 2.4 5 595 320000 0.72 — 550 354000 0.64 — 565 340000 0.50 — aExtrapolated from literature values.using SiMe4 as an internal standard in stated solvents. 10% K2CO3 solution (75 ml). This was extracted with diethyl ether (3×50 ml), dried and reduced to leave a colourless oil. Multiplicities are represented by the following abbreviations: s, singlet; d, doublet; t, triplet, q, quartet; m, multiplet; br, Purification by vacuum distillation gave unreacted pyridine-4- carbaldehyde, bp 73–74°C, 0.5 mmHg and 4-(diethoxymethyl)- broad signal.Coupling constants, (J) are given in Hz. pyridine as a colourless oil, bp 75–76 °C, 0.5 mmHg, 19 g, 81%; dH (250 MHz, CDCl3) 1.25(t, 6H, J 7, 2Me); 3.58[m, 4H, 4-(Diethoxymethyl ) pyridine 2(OCH2Me)]; 5.50[s, 1H, pyridine-CH-(OEt)2]; 7.40(d, 2H, J This compound was prepared by adapting the procedure of 6, pyridine); 8.70(d, 2H, J 6, pyridine); dC (63 MHz, CDCl3) Popp and McEwen,17 but full experimental details are given 15.0(q, 2C, 2Me); 61.2[t, 2C, 2(OCH2Me]; 99.8[d, 1C, pyri- below.A 13.5% solution of hydrogen bromide in ethanol was dine-CH-(OEt)2]; 121.6(d, 2C, pyridine); 147.6(s, 1C, pyridine); prepared by cooling ethanol (88 ml) to 0°C under nitrogen 149.9(d, 2C, pyridine); m/z (EI) 181(M+, 90%).and adding acetyl bromide (12 ml) dropwise. To a portion of this solution (52 ml) pyridine-4-carbaldehyde (11.2 g, N-Butyl-4-(diethoxymethyl )pyridinium bromide 105 mmol) was added to give a white precipitate and a yellow 4-(Diethoxymethyl)pyridine (4 g, 22.0 mmol) was dissolved in solution which was stirred at 20°C for 90 h. Dry benzene dry ethanol (10 ml) and 1-bromobutane (4.56 g, 33.0 mmol) (100 ml) was then added and any water formed during the added.The mixture was heated at reflux for 16 h. The ethanol reaction, removed by azeotropic distillation through a Soxhlet and excess 1-bromobutane were evaporated under reduced extractor containing MgSO4 , over a period of 24 h. Benzene pressure. The resulting yellow oil was left under high vacuum and ethanol were evaporated under reduced pressure to give an orange solid which was made alkaline (pH 9) by adding to remove any remaining solvent to give N-butyl-4-(diethoxy- J.Mater. Chem., 1997, 7(3), 391–401 395methyl)pyridinium bromide, (6.0 g, 85%), dH (250 MHz, 2-yl)pyridinium bromide remained contaminated with pro- CDCl3) 0.95[t, 3H, N(CH2)3CH3]; 1.25[t, 6H, 2(OCH2CH3)]; pane-1,3-diol, m/z (+ve FAB MS) C13H20NO2 222 (M+, 1.45[m, 2H, N(CH2)2CH2Me]; 2.05(m, 2H, NCH2CH2C2H5); 100%). 2.70(2H, br s, H2O); 3.65[q, 4H, 2(OCH2CH3)]; 5.05(t, 2H, NCH2C3H7); 5.70(s, 1H, (OEt)2-CH-pyridine); 8.15(d, 2H, pyri- 6-(1,3-Dioxan-2-yl )azulene, 1b dine); 9.60(d, 2H, pyridine); dC (63 MHz, CHCl3) 12.7(q, 1C, C3H7CH3);14.2[q, 2C, 2(OCH2CH3)]; 18.4(t, 1C, CH2); 32.9(t, Freshly distilled cyclopentadiene (2.19 ml, 33.2 mmol) was 1C, CH2); 33.0(t, 1C, CH2 ); 60.2(t, 1C, CH2); 61.5[t, 2C, added dropwise to sodium hydride (0.40 g, 16.7 mmol) in THF 2(OCH2CH3)]; 91.3(d, 1C, (OEt)2-CH-pyridine); 97.4(d, 2C, (30 ml) at 0°C over 30 min and then allowed to warm to 2-pyridine); 125.3(d, 2C, 3-pyridine); 156.7(s, 1C, 4-pyridine); 20°C.Crude N-butyl-4-(1,3-dioxan-2-yl)pyridinium bromide m/z (+ve FAB MS) C14H24NO2 238 (M+, 100%).(1.9 g, 6.28 mmol), dissolved in THF (10 ml), was then added to the pink solution giving a colour change to dark orange and then brown. The mixture was heated at reflux for 3 h. 6-(Diethoxymethyl ) azulene, 1a Water (50 ml) was then added and the mixture extracted with dichloromethane (4×50 ml): the combined organic layers Freshly distilled cyclopentadiene (2.42 g, 36.6 mmol) was added were dried and solvent evaporated under reduced pressure.dropwise over 30 min to sodium hydride (0.88 g, 36.6 mmol) Purification by column chromatography on silica using in THF (70 ml) at 0°C and then allowed to warm to 20°C. dichloromethane as eluent gave 6-(1,3-dioxan-2-yl)azulene as N-butyl-4-(diethoxymethyl)pyridinium bromide (17.5 g, dark blue microprisms.Recrystallisation from pentane gave 55.0 mmol) dissolved in THF (50 ml) was then added to the the pure product, (0.195 g, 15%), mp 110–111°C (Found: C, pinkish solution which went dark red and then brown. The 78.3; H, 6.6; C14H14O2 calculated: C, 78.5; H, 6.6%); dH mixture was heated at reflux for 3 h, a blue spot being indicated (250 MHz, CDCl3) 1.45(m, 1H, dioxanyl); 2.25(m, 1H, diox- by TLC.THF was evaporated under reduced pressure to leave anyl); 4.00(m, 2H, dioxanyl); 4.30(m, 2H, dioxanyl); 5.50(s, a black viscous oil to which silica was added. Purification by 1H, H-C-azulene); 7.40(d, 2H, J 10, azulene H-C1,3); 7.40(d, column chromatography using light petroleum (bp 40–60°C) 2H, J 4, azulene H-C5,7 ); 7.90(t, 1H, J 4, azulene H-C2); 8.40(d, as eluent gave 6-(diethoxymethyl)azulene as a dark blue oil 2H, J 10, azulene H-C4); dC (60 MHz, CDCl3) 25.7(t, 1C, (2.72 g, 32%).Further purification using a Ku� gelrohr appar- CH2); 67.6 [t, 2C, (OCH2)2]; 104.3(d, 1C, H-C-azulene); atus gave 1a (Found: C, 78.0; H, 7.9. C15H18O2 calculated: C, 118.1(d, 2C, azulene C1,3); 121.1(d, 2C, azulene C5,7); 135.2(d, 78.2, H, 7.9%), dH (250 MHz, CDCl3) 1.25(t, 6H, 2Me); 3.6[m, 2C, azulene C4,8); 135.9(d, 1C, azulene C2 ); 140.1(s, 2C, azulene 4H, 2(OCH2CH3)]; 5.45[s, 1H, HC(OEt)2]; 7.40(m, 4H, azu- C3a,8a); 146.0(s, 1C, azulene C6); m/z (EI) 214 (M+, 83%).lene H-C1,3,5,7); 7.90(t, 1H, J 4, azulene H-C2); 8.35 (d, 2H, azulene H-C4,8 ); dC (60 MHz, CDCL3) 15.2 (q, 1C, Me); 61.8[t, 2C, (OCH2Me)2]; 104.4[d, 1C, H-C(OEt)2 ]; 118.1(d, 2C, azu- cis- and trans-6-(5-Pentyl-1,3-dioxan-2-yl )azulene, 1c lene C1,3 ); 121.4(d, 2C, azulene C5,7); 135.8(d, 2C, azulene C4,8); 137.3(s, 1C, azulene C2); 139.9(s, 2C, azulene C3a,8a); Compound 1a (0.35 g, 1.52 mmol) and 2-pentylpropane-1,3- 147.3(s, 1C, azulene C6); m/z (EI) 230 (M+, 80%).diol (0.33 g, 2.28 mmol) were stirred together in dry benzene (10 ml) with an ion exchange resin (catalytic amount) at 100°C for 6 h and the reaction was followed by TLC.Purification of the products was attempted by column chromatography on 4-(1,3-Dioxan-2-yl )pyridine silica using hexane–dichloromethane (351) as eluent which A 13.5% solution of HBr in propane-1,3-diol was prepared by gave the mixture of isomers as blue microprisms (170 mg, cooling propane-1,3-diol (88 ml) to 0°C under nitrogen and 39%).These were shown, by analytical HPLC, to be a mixture adding acetyl bromide (12 ml) dropwise. To a portion of this of the cis- and trans-forms in a ratio of 253. Separation was solution (52 ml) was added pyridine-4-carbaldehyde (11.2 g, achieved using reverse phase HPLC to give the pure isomers, 105 mmol) and the solution was stirred at 20 °C for 90 h.Dry cis-6-(5-pentyl-1,3-dioxan-2-yl)azulemp 81.4°C; (M+ benzene (100 ml) was then added and any water formed during Found: 284.1785, C19H24O2 requires: 284.17762); dH (250 MHz, the reaction, removed by azeotropic distillation through a CD2Cl2) 0.9(t, 3H, J 7, Me); 1.35[m, 7H, CH2(CH2)3Me, C- Soxhlet extractor containing MgSO4, over a period of 24 h.HC5H9]; 1.83(m, 2H, CH2C4H9 ); 4.10(m, 4H, (OCH2)2];5.52(s, Benzene and ethanol were then evaporated under reduced 1H, H-C-azulene); 7.38(d, 2H, J 4, azulene H-C1,3); 7.38(d, 2H, pressure to give an orange solid which was made alkaline J 10, azulene H-C5,7); 7.90(t, 1H, J 4, azulene H-C2); 8.37(d, (pH 9) by adding 10% K2CO3 solution (75 ml). This was 2H, J 10, azulene H-C4,8 ); dC (63 MHz, CD2Cl2 ) 14.1(q, 1C, extracted with diethyl ether (3×50 ml), dried and reduced Me); 22.7(t, 1C, CH2); 27.3(t, 1C, CH2 ) 29.6(t, 1C, CH); 32.0(t, to leave a brown oil.Purification by vacuum distillation 1C, CH2 ); 34.4[d, 1C, HC(CH2O)2]; 71.0(t, 2C, (CH2O)2 ]; gave unreacted pyridine-4-carbaldehyde and a small amount 104.7(d, 1C, H-C-azulene); 118.2(d, 2C, azulene C1,3); 121.2(d, of product, bp 68–71 °C at 0.6 mmHg (3.62 g, 21%) as a 2C, azulene C5,7); 136.1(d, 2C, azulene C4,8); 137.6(d, 1C, mixture of 4-(1,3-dioxan-2-yl)pyridine (1.05 g, 6.1% from azulene C2); 140.1(s, 2C, azulene C3a,8a); 146.0(s, 1C, azulene 1H NMR) and propane-1,3-diol as a colourless oil at C6); m/z (EI) 284 (M+, 92%); and trans-6-(5-pentyl-1,3-dioxan- 71–100°C at 0.6 mmHg, dH (220 MHz, CDCl3); 1.70(m, 2H, 2-yl) azulene, mp 100.1°C; (M+ Found: 284.1783, C19H24O2 OCH2CH2CH2O); 4.0(m, 4H, OCH2CH2CH2O); 5.50(s, 1H requires: 284.17762); dH (250 MHz, CD2Cl2) 0.90(t, 3H, J 7, 1,3-dioxan-2-yl-CH-pyridine); 7.70(d, 2H, 2-pyridine); 8.70(d, Me); 1.10(m, 2H, C3H7CH2Me); 1.30[m, 6H, (CH2 )3C2H5 ]; 2H, 3-pyridine); and signals for propane-1,3-diol; m/z (+CI) 2.20(m, 1H, C-HC5H9); 3.58(t, 2H, J 12, OCH2); 4.28(q, 2H, C9H11NO2 165 (M+, 100%).J 4.5, OCH2); 5.45(s, 1H, H-C-azulene); 7.38(d, 2H, J 4, azulene H-C1,3); 7.38(d, 2H, J 10, azulene H-C5,7); 7.90(t, 1H, J 4, azulene H-C2); 8.35(d, 2H, J 10, azulene H-C4,8 ); dC (63 MHz, N-Butyl-4-(1,3-dioxan-2-yl ) pyridinium bromide CD2Cl2) 14.1(q, 1C, Me); 22.5(t, 1C, CH2); 26.0(t, 1C, CH2 ); 28.2(t, 1C, CH); 32.0(t, 1C, CH2); 34.2[d, 1C, HC(CH2O)2 ]; The crude mixture of 4-(1,3-dioxan-2-yl)pyridine (1.05 g, 72.9[t, 2C, (CH2O)2]; 104.3(d, 1C, H-C-azulene); 118.2(d, 2C, 6.36 mmol) and 1-bromobutane (4.5 g, 33.0 mmol) was added azulene C1,3 ); 121.2 (d, 2C, azulene C5,7); 136.0(d, 2C, azulene to dry ethanol (10 ml) and heated at reflux for 16 h, the C4,8 ); 137.6(d, 1C, azulene C2); 140.1(s, 2C, azulene C3a,8a); reaction being followed by TLC. The ethanol was evaporated under reduced pressure but the product N-butyl-4-(1,3-dioxan- 145.9(s, 1C, azulene C6); m/z (EI) 284 (M+, 100%). 396 J. Mater. Chem., 1997, 7(3), 391–401The series of homologues were all prepared in a similar H-C1,3,5,7 and phenyl); 7.95(t, 1H azulene H-C2); 8.45(d, 2H, azulene H-C4,8); dC (63 MHz, CDCl3) 41.1(d, 1C, H-C-Ph); manner and the reaction conditions are outlined in Table A.Table A 72.6[t, 2C, (OCH2)2]; 104.2(d, 1C, H-C-azulene); 118.3(d, 2C, azulene C1,3); 121.2(d, 2C, azulene C5,7); 127.6(d, 1C, Ph); temperature/°C, cis5trans 127.7(d, 2C, Ph); 128.9(d, 2C, Ph); 136.0(d, 2C, azulene C4,8 ); compound catalyst solvent time/h yield (%) ratio 137.4(s, 1C, Ph) 137.7(d, 1C, azulene C2 ); 140.2(s, 2C, azulene C3a,8a); 145.6(s, 1C, azulene C6); m/z (EI) 290 (M+, 85%). 1d TsOH — 55/48 22 253 1e i-e resin Benzene 80/20 16 255 This procedure was used to prepare 1m and 1n (Table C) 1f i-e resin CH2Cl2 50/20 13 153 by reaction with the appropriate diol. 1g i-e resin Benzene reflux/4 23 153 1h i-e resin Benzene reflux/8 6 153 cis- and trans-6-[5-(4-Hexyloxyphenyl )-1,3-dioxan-2-yl]- 1i i-e resin Benzene 100/8 26 153 1j i-e resin Toluene reflux/4 41 153 azulene, 1m 1k i-e resin Toluene 100/8 39 153 cis-6-[5-Hexyloxyphenyl)-1,3-dioxan-2-yl]azulene, mp 143 °C (decomp.) and the trans-6-[5-(4-hexyloxyphenyl)-1,3-dioxan- All the above compounds gave 1H NMR, 13C NMR and mass 2-yl]azulene, mp 225°C, dH (250 MHz, CD2Cl2) 0.89(t, 3H, spectra analogous to those for the 6-(5-pentyl-1,3-dioxan-2- J 7, Me); 1.40[m, 6H, C2H4(CH2)3Me]; 1.75(m, 2H, yl)azulene isomers described above.CH2CH2C4H9 ); 3.33(m, 1H, H-C-phenyl); 3.92(t, 2H, J 7, The high resolution mass spectra values for each compound dioxanyl CH2); 4.02(t, 2H, J 11.5, OCH2C5H11); 4.32(q, 2H, J are given in Table B. 11.5, dioxanyl CH2); 5.6(s, 1H, H-C-azulene); 6.86(d, 2H, J 8.5, Table B phenyl); 7.16(d, 2H, J 8.5, phenyl); 7.38(d, 2H, J 4.5, azulene H-C1,3); 7.42(d, 2H, J 10.5, azulene H-C5,7); 7.9(t, 1H, J 4.5, molecular found found azulene H-C2); 8.39(d, 2H, J 10.5, azulene H-C4,8 ); dC (63 MHz, compound formula calc. cis trans CD2Cl2) 14.2(q, 1C, Me); 23.0(t, 1C, CH2); 26.1(t, 1C, CH2 ); 1d C20H26O2 298.1933 298.1941 298.1926 29.6(t, 1C, CH2); 32.0(t, 1C, CH2); 40.7[t, 1C, H-C-(OCH2)]; 1e C24H34O2 354.2559 354.2542 354.2547 68.5(t, 1C, OCH2 ); 73.1[d, 2C, dioxanyl 2(OCH2)]; 104.3(d, 1f C25H36O2 368.2715 368.2719 368.2711 1C, H-C-azulene); 115.1(d, 2C, phenyl); 118.5(d, 2C, azulene 1g C26H38O2 382.2872 382.2882 382.2862 C1,3 ); 121.6(d, 2C, azulene C5,7); 129.0(d, 2C, phenyl); 129.6(s, 1h C27H40O2 396.3028 396.3046 396.3012 1C, phenyl); 136.2(d, 2C, azulene C4,8 ); 138.0(d, 1C, azulene 1i C28H42O2 410.3185 410.3178 410.3166 1j C29H44O2 424.3341 424.3348 424.3346 C2); 140.4(s, 2C, azulene C3a,8a); 146.4(s, 1C, phenyl); 158.9(s, 1k C30H46O2 438.3498 438.3489 438.3490 1C, azulene C6); m/z (EI) 390 (M+, 62%).cis- and trans-6-(5-Phenyl-1,3-dioxan-2-yl ) azulene, 1l cis- and trans-6-[5-(4-dodecyloxyphenyl )-1,3-dioxan-2-yl]- azulene, 1n Compound 1a and 2-phenylpropane-1,3-diol (0.5 g, 3.26 mmol) were stirred together with the ion-exchange catalyst at 60°C cis-6-[5-(4-Dodecyloxyphenyl)-1,3-dioxan-2-yl]azulene, mp 127°C (M+ Found: 474.3139, C32H42O3 calculated: 474.3134); in dry THF (5 ml) for 2 h.The reaction was monitored by TLC; when all the starting material had disappeared the dH (250 MHz, CD2Cl2) 0.86(t, 3H, J 7, Me); 1.26[m, 18H, CH2(CH2 )9Me]; 1.75(m, 2H, CH2CH2C9H18Me); 2.75(m, 1H, reaction mixture was filtered to remove the resin and the product washed through with ethyl acetate.Purification by CH-phenyl-OC12H25); 3.94(t, 2H, OCH2C11H23); 4.38[m, 4H, 2(dioxanyl CH2)]; 5.68(s, 1H, dioxanylMCHMazulene); 6.89(d, column chromatography on silica, using light petroleum (bp 40–60°C)–ethyl acetate, 451, as eluent gave a mixture of 2H, J 9, phenyl); 7.39(m, 4H, azulene H-C1,3,5,7); 7.53(d, 2H, J 9, phenyl); 7.90(t, 1H, J 4, azulene H-C2); 8.39(d, 2H, J 11, the cis- and trans-isomers as dark blue microprisms, 0.532 g, 53%.These were shown, by analytical HPLC to be a mixture azulene H-C4,8 ); dC (63 MHz, CD2Cl2) 14.25(q, 1C, Me); 23.1(t, 1C, CH2); 26.4(t, 1C, CH2); 29.7[t, 2C, 2(CH2 )]; 29.8[t, 4C, of the cis- and trans-forms in a ratio 152.Separation of the isomers was achieved by reverse phase chromatography; recrys- 4(CH2)]; 30.0(t, 1C, CH2); 32.3(t, 1C, CH2); 38.6(t, 1C, dioxanyl- CH phenyl-OC12H25); 68.4(t, 1C, OCH2C11H23); 72.2[d, tallisation from diethyl ether–light petroleum gave the pure isomers; cis-6-(5-phenyl-1,3-dioxan-2-yl)azulene, mp 123 °C 2C, dioxanyl 2(OCH2)]; 104.8(d, 1C, dioxanyl-HC-azulene); 114.6(d, 2C, phenyl); 118.5(d, 2C, azulene C1,3); 121.6(d, 2C, (M+ Found: 290.1302, C20H18O2 calculated: 290.1307); dH (250 MHz, CDCl3 ) 2.75(m, 1H, dioxanyl); 4.4(m, 4H, diox- azulene C5,7); 129.7(d, 2C, phenyl); 135.2(s, 1C, phenyl); 136.3(d, 2C, azulene C4,8); 138.0(d, 1C, azulene C2); 140.4(s, anyl); 5.79(s, 1H, H-C-azulene); 7.7(m, 2H, phenyl); 7.47(d, 2H, J 11, azulene H-C5,7); 7.35(m, 5H, phenyl and azulene H- 2C, azulene C3a,8a); 146.5(s, 1C, phenyl); 158.3(s, 1C, azulene C6); m/z (EI) 474 (M+, 100%); and trans-6-[5-(4-dodecyloxy- C1,3); 7.9(t, 1H, J 4, azulene H-C2); 8.45(d, 2H, J 11, azulene H-C4,8); dC (63 MHz, 2H6 acetone) 39.5(d, 1C, H-C-Ph); 72.1[t, phenyl)-1,3-dioxan-2-yl]azulene, mp 206 °C (crystal SB) (M+ Found: 474.3123, C32H42O3 calculated: 474.3134); dH 2C, (OCH2 )2 ]; 104.9(d, 1C, H-C-azulene); 118.8(d, 2C, azulene C1,3); 122.2(d, 2C, azulene C5,7); 126.9(d, 1C, Ph); 128.9(d, 2C, (250 MHz, CD2Cl2) 0.88(t, 3H, J 7, Me); 1.30[m, 18H, CH2(CH2 )9Me]; 1.75(m, 2H, CH2CH2C9H18Me); 3.34(m, 1H, Ph); 129.2(d, 2C, Ph); 136.5(d, 2C, azulene C4,8); 138.1(s, 1C, Ph); 140.8(d, 1C, azulene C2); 144.3(s, 2C, azulene C3a,8a); CH-phenyl-OC12H25); 3.94(t, 2H, J 7, OCH2C11H23); 4.04(t, 2H, J 11.5, dioxanyl CH2 ); 4.34(q, H, J 4.5, dioxanyl CH2 ); 147.4(s, 1C, azulene C6); m/z (EI) 290 (M+, 45%); and trans- 6-(5-phenyl-1,3-dioxan-2-yl)azulene, mp 193 °C (M+ Found: 5.68(s, 1H, dioxanyl-CH-azulene); 6.88(d, 2H, J 9, phenyl); 7.17(d, 2H, J 9, phenyl); 7.42(m, 4H, azulene H-C1,3,5,7); 7.92(t, 290.1302, C20H18O2 calculated: 290.1307); dH (250 MHz, CDCl3) 3.45(m, 1H, dioxanyl); 4.10(t, 2H, dioxanyl); 4.45(q, 1H, J 4, azulene H-C2); 8.40(d, 2H, J 11, azulene H-C4,8); dC (63 MHz, CD2Cl2) 14.24(q, 1C, Me); 23.1(t, 1C, CH2); 26.4(t, 2H, dioxanyl); 5.65(s, 1H, H-C-azulene); 7.30(m, 9H, azulene Table C compound alkyl chain catalyst solvent temperature/°C, time/h yield (%) cis5trans 1m OC6H13 i-e resin THF 60/48 7 154 1n OC12H25 i-e resin THF 100/8 14 153 J.Mater. Chem., 1997, 7(3), 391–401 3971C, CH2); 26.4(t, 1C, CH2); 29.6[t, 2C, 2(CH2)]; 29.7[t, 4C, CDCl3) 14.1(q, 1C, Me); 21.3(q, 1C, Me); 21.4(q, 1C, Me); 22.7(q, 1C, Me); 22.8(t, 1C, CH2); 26.4(t, 1C, CH2); 26.9(t, 1C, 4(CH2)]; 30.0(t, 1C, CH2); 32.3(t, 1C, CH2); 40.7(t, 1C, diox- CH2); 28.2(t, 1C, CH2); 29.4(t, 1C, CH2); 29.5(t, 1C, CH2 ); anyl-HC phenyl-OC12H25); 68.4(t, 1C, OCH2C11H23); 73.1(d, 29.7(t, 4C, CH2); 29.8(t, 1C, CH2); 30.5(d, 1C, CH); 31.9(t, 1C, 2C, dioxanyl 2(OCH2)); 104.3(d, 1C, dioxanyl-HC-azulene); CH2); 34.2(d, 1C, CH); 35.7(t, 1C, CH2); 39.6(d, 1C, CH); 115.1(d, 2C, phenyl); 118.5(d, 2C, azulene C1,3); 121.6(d, 2C, 42.9[t, 1C, H-C(CH2O)2 ]; 48.2(d, 1C, neomenthyl H-C-azu- azulene C5,7); 129.0(d, 2C, phenyl); 129.6(s, 1C, phenyl); lene); 72.9[t, 2C, 2(OCH2Me)]; 104.6(d, 1C, dioxanyl H-C- 136.2(d, 2C, azulene C4,8 ); 138.0(d, 1C, azulene C2); 140.4(s, azulene); 119.6(d, 2C, azulene C1,3); 121.2(d, 2C, azulene C5,7); 2C, azulene C3a,8a); 146.4(s, 1C, phenyl); 158.9(s, 1C, azulene 133.7(d, 2C, azulene, C4,8 ); 139.7(s, 2C, azulene C3a,8a); 144.0(s, C6); m/z (EI) 474 (M+, 100%). 1C, azulene C6); 158.5(s, 1C, azulene C2); m/z (EI) 506 (M+, 18%). 2-(+)-Neomenthyl-6-(diethoxymethyl) azulene (+)-Neomenthylcyclopentadiene18 (2 g, 9.8 mmol, 1.1 equiv.) 1-Cyclohexyl-6-(diethoxymethyl) azulene and 2-cyclohexyl-6- was added to sodium hydride (0.21 g, 8.90 mmol, 1 equiv.) in (diethoxymethyl )azulene dry THF (30 ml) at 20°C to give a slightly pink solution.After Cyclohexylcyclopentadiene, (1 g, 6.76 mmol) was added to 30 min, when no further reaction was observed, N-butyl-4- sodium hydride (0.2 , 8.33 mmol) in THF (30 ml) and heated (diethoxymenthyl)pyridinium bromide (5.0 g, 15.0 mmol, 2 gently until the reaction had completed, to give a red solution.equiv.) in THF (20 ml) was added to give a dark brown Butyl-4-(diethoxymethyl)pyridine bromide (5.0 g, 15.0 mmol) solution which was heated at reflux for 16 h. Solvent was was added in THF (25 ml) and heated at reflux for 90 h. evaporated under reduced pressure and alumina added. Solvent was evaporated under reduced pressure and neutral Purification by column chromatography was attempted on silica added to the dark brown oil.Purification by column basic alumina using hexane as eluent to give an unidentified chromatography on neutral silica using light petroleum as yellow oil and 2-(+)-neomenthyl-6-(diethoxymenthyl)azulene eluent gave a colourless oil identified as N-butyl-(4-ethoxycar- as a dark blue oil 0.74 g, 22.6% (Found: 368.2706, C25H36O2 bonyl-4-ethyl)dihydropyridine, 0.5 ml, 14%, dH (250 MHz, calculated: 368.2715); dH (250 MHz, CDCl3 ) 0.8(t, 6H, 2Me); CDCl3) 0.81(t, 3H, J 7.5, CH2CH3); 0.89(t, 3H, J 7.5, 1.30(m, 18H, neomenthyl); 2.20(m, 1H, neomenthyl H-C-azu- NC3H6CH3); 1.24(t, 3H, J 7.5, COOCH2CH3); 1.27(m, lene); 3.60(t, 2H, OCH2); 3.55[m, 4H, 2(OCH2Me)]; 7.30(s, 2H, NC2H4CH2Me); 1.44(m, 2H, NCH2CH2C2H5); 1.49(q, 2H, azulene H-C1,3); 7.35(d, 2H, azulene H-C5,7); 8.25(d, 2H, 2H, J 7.5, CH2Me); 3.20(t, 2H, J 7, NCH2C3H7); 4.13(q, azulene H-C4,8); dC (63 MHz, CDCl3 ) 15.2(q, 2C, Me); 21.3(q, 2H, J 7, COOCH2Me); 4.40(d, 2H, J 8, b-dihydropyridine); 1C, Me); 21.4(q, 1C, Me): 22.8(q, 1C, Me); 26.5(t, 1C, CH2); 5.93(d, 2H, J 8, a-dihydropyridine); dC (63 MHz, CDCl3) 26.9(d, 1C, CH); 30.5(d, 1C, CH); 35.7(t, 1C, CH2); 39.6(d, 1C, 8.5(q, 1C, CH2CH3); 13.8(q, 1C, NC3H6CH3); 14.1(q, CH); 43.0(t, 1C, CH2 ); 48.2[d, 1C, (+)-neomenthyl H-C- 1C, COOCH2CH3); 19.7(t, 1C, NC2H4CH2Me); 32.3(d, 1C, azulene]; 61.9[t, 2C, 2(OCH2)Me]; 104.5(d, 1C, diethoxy H- NCH2CH2C2H5); 35.1(t, 1C, CH2Me); 46.6(s, 1C, c-dihydro- C-azulene); 119.6(d, 2C, azulene C1,3 ); 121.5(d, 2C, azulene pyridine); 53.1(t, 1C, NCH2C3H7); 60.4(t, 1C, OCH2Me); C5,7); 133.6(d, 2C, azulene C4,8); 139.5(s, 2C, azulene C3a,8a); 98.4(d, 2C, b-dihydropyridine); 130.2(d, 2C, a-dihydropyridine); 145.3(s, 1C, azulene C6); 158.3(s, 1C, azulene C2); m/z (EI) 368 176.5(s, 1C, COOEt), and a mixture of the isomers as a dark- (M+, 50%).blue oil, 0.533 g, 25%.Separation of the isomers was achieved by MPLC to give 1-cyclohexyl-6-(diethoxymethyl)azulene, as cis- and trans-2-Neomenthyl-6-(5-undecyl-1,3-dioxan-2-yl )- a purple–blue oil, (Found: 312.2103, C21H28O2 calculated: azulene, 1o 312.2089); dH (250 MHz, CD2Cl2) 1.30[t, 6H, 2(OCH2Me)]; 1.70(m, 10H, cyclohexyl); 3.25(m, 1H, azulene CH-cyclohexyl); 2-Neomenthyl-6-(diethoxymethyl)azulene (0.6 g, 1.63 mmol) 3.55[m, 4H, 2(OCH2Me)]; 5.35[s, 1H, (EtO)2CH-azulene]; and 2-undecylpropane-1,3-diol (0.6 g, 2.61 mmol) were heated 7.15(d, 2H, azulene H-C5,7 ); 7.2(d, 1H, azulene H-C3); 7.75(d, to 60°C together with an ion-exchange resin (catalytic amount) 1H, azulene H-C2); 8.15(d, 1H, azulene H-C4); 8.25(d, 1H, in dry ethyl acetate (3 ml) for 1 h.The reaction was monitored azulene H-C4); dC (63 MHz, CD2Cl2) 15.4[q, 2C, 2(OCHMe)]; by TLC and solvent evaporated under reduced pressure when 26.8(t, 1C, cyclohexyl); 27.6(t, 2C, cyclohexyl); 35.6(t, 2C, starting material had disappeared. Purification was achieved cyclohexyl); 37.0(d, 1C, azulene CH-cyclohexyl); 62.4[t, 2C, by column chromatography on neutral silica using light pet- 2(OCH2Me)]; 105.1[d, 1C, (EtO)2CH-azulene]; 117.3(d, 1C, roleum–diethyl ether, 451, as eluent to give the mixture of azulene C3); 120.1(d, 1C, azulene C5); 120.8(d, 1C, azulene C7); isomers as blue microprisms, 150 mg, 18%.Separation of the 132.6(d, 1C, azulene C2); 134.6(s, 1C, azulene C1); 135.1(d, 1C, isomers (cis/trans: 1/3) was achieved by HPLC to give cis-2- azulene C4); 135.8(d, 1C, azulene C8); 137.9(s, 1C, azulene neomenthyl-6-(5-undecyl-1,3-dioxan-2-yl)azulene, as a blue oil, C3a); 140.6(s, 1C, azulene C8a); 148.0(s, 1C, azulene C6 ); m/z dH (250 MHz, CDCl3) 1.30(m, 43H, neomenthyl and C11H23); (EI) 312 (M+, 100%), and 2-cyclohexyl-6-(diethoxymethyl)- 4.05[s, 4H, 2(OCH2)]; 5.45(s, 1H, dioxanyl H-C-azulene); azulene, as blue microprisms, mp 58–59 °C (Found 312.2074, 7.20(s, 2H, azulene H-C1,3); 7.25(d, 2H, azulene H-C5,7); 8.25(d, C21H28O2 calculated: 312.2089); dH (250 MHz, CD2Cl2) 0.90[t, 2H, azulene H-C4,8); dC (63 MHz, CDCl3 ) 14.1(q, 1C, Me); 6H, 2(OCH2Me)]; 1.80(m, 10H, cyclohexyl); 2.90(m, 1H, azu- 21.2(q, 1C, Me); 21.4(q, 1C, Me); 22.7(q, 1C, Me); 22.8(t, 1C, lene CH-cyclohexyl); 3.65[m, 4H, 2(OCH2Me)]; 4.45 [s, 1H, CH2); 26.4 (t, 1C, CH2); 26.9 (t, 1C, CH2); 27.6 (t, 1C, CH2); (EtO)2CH-azulene]; 7.20(s, 2H, azulene H-C1,3); 7.30(d, 2H, 28.2 (t, 1C, CH2); 29.4(t, 1C, CH2); 29.7[t, 5C, 5(CH2)]; 30.5(d, azulene H-C5,7); 8.20(d, 2H, azulene H-C4,8); dC (63 MHz, 1C, CH); 31.9(t, 1C, CH2); 34.4(d, 2C, CH); 35.7(t, 1C, CH2); CD2Cl2) 5.2[q, 2C, 2(OCH2Me)]; 16.6(t, 1C, cyclohexyl); 39.6(d, 1C, CH); 42.9[t, 1C, H-C(CH2O)2]; 48.2(d, 1C, neo- 16.9(t, 2C, cyclohexyl); 24.5(t, 2C, cyclohexyl); 30.3(d, 1C, menthyl H-C-azulene); 70.9[t, 2C, 2(OCH2Me)]; 104.9(d, 1C, azulene CH-cyclohexyl); 94.9[t, 2C, 2(OCH2Me)]; 106.0[d, dioxanyl H-C-azulene); 119.6(d, 2C, azulene C1,3 ); 121.2(d, 2C, 1C, (EtO)2CH-azulene]; 111.7(d, 2C, azulene C1,3); 123.9(d, azulene C5,7); 133.8(d, 2C, azulene C4,8); 139.7(s, 2C, azulene 2C, azulene, C5,7); 130.3(d, 2C, azulene C4,8); 130.3(s, 2C, C3a,8a); 144.2(s, 1C, azulene C6); 158.5(s, 1C, azulene C2); and azulene C3a,8a); 135.9(s, 1C, azulene C6); 151.4(s, 1C, azulene trans-2-neomenthyl-6-(5-undecyl-1,3-dioxan-2-yl)azulene, as C2); m/z (EI) 312 (M+, 100%).blue microprisms, mp 53–43 °C, dH (250 MHz, CDCl3) 1.30(m, cis- and trans-2-Cyclohexyl-6-(5-tridecyl-1,3-dioxan-2-yl )- 42H, neomenthyl and C11H23); 2.20(m, 1H, neomenthyl H-Cazulene, 1p azulene); 3.60(t, 2H, OCH2); 4.30(q, 2H, OCH2); 5.45(s, 1H, dioxanyl H-C-azulene); 7.30(s, 2H, azulene H-C1,3); 7.35(d, 2H, 2-Cyclohexyl-6-(diethoxymethyl)azulene (0.28 g, 0.90 mmol) and tridecylpropane-1,3-diol (0.3 g, 1.15 mmol) were dissolved azulene H-C5,7 ); 8.25(d, 2H, azulene H-C4,8); dC (63 MHz, 398 J.Mater. Chem., 1997, 7(3), 391–401in dry benzene (20 ml) and heated at 80°C with an ion to give colourless crystals of 4-(ethylenedioxy)cyclohexyl tosylate, 7.2 g, 73%, dH (250 MHz, CDCl3) 1.75(m, 8H, cyclohexyl exchange resin (catalytic amount) for 3 h. Solvent was evaporated under reduced pressure to leave a black product.CH2s); 2.45(s, 3H, Me); 3.90(m, 4H, ketal CH2s); 4.60(m, 1H, HCOTs); 7.30(d, 2H, phenyl); 7.80(d, 2H, phenyl): m/z (EI) Purification was attempted by column chromatography on neutral silica using light petroleum with 1% diethyl ether as 211 (M+, 25%). eluent to give the pure trans-2-cyclohexyl-6-(5-tridecyl-1,3- 4-(Ethylenedioxy)cyclohexylcyclopentadiene dioxan-2-yl)azulene, as blue microprisms (Found: C, 82.73; H, 10.80; C33H50O2 calculated: C, 82.79; H, 10.52%); dH (250 MHz, This was prepared by following the literature procedure for CD2Cl2) 0.80(t, 3H, J 7, Me); 1.1(m, 2H, cyclohexyl CH2); the synthesis of (+)-neomenthylcyclopentadiene by Cesarotti 1.20(m, 22H, C11H22C2H5 ); 1.45(m, 6H, cyclohexyl); 1.70(m, and Kagan,19 but full experimental details are given below. 4H, cyclohexyl); 2.05(m, 1H, HC-C13H27); 2.85(m, 1H, azulene Freshly distilled cyclopentadiene (12 ml, 0.177 M) was added CH-cyclohexyl); 3.46(t, 2H, J 11 Hz, OCH2 ); 4.16(q, 2H, J 5, dropwise to sodium hydride (3.4 g, 0.142 M) in THF (25 ml) at OCH2); 5.70(s, 1H, dioxanyl HC-azulene); 7.14(s, 2H, azulene 0°C to give a pink solution. When the reaction had completed H-C1,3); 7.21(d, 2H, J 10.5, azulene H-C5,7 ); 8.13(d, 2H, J this was syringed into a solution of 4-(ethylenedioxy)cyclohexyl 10.5 Hz), azulene H-C4,8); dC (63 MHz, CD2Cl2) 14.3(q, 1C, tosylate (11 g, 35.5 mmol) in THF (50 ml) and heated at reflux Me), 23.1(t, 1C, CH2); 26.7(t, 1C, cyclohexyl); 27.1(t, 2C, for 16 h to leave dark red colour.Water was then added, the cyclohexyl); 28.5(t, 1C, CH2); 29.7(t, 1C, CH2 ); 29.9[t, 8C, now dark brown solution filtered through a Bu� chner funnel 8(CH2)]; 30.1(t, 1C, CH2); 32.3(t, 2C, cyclohexyl); 34.6(d, 1C, and solvent evaporated from the filtrate under reduced pressure HC-C13H27); 40.5(d, 1C, azulene CH-cyclohexyl); 73.2[t, 2C, to leave a brown oil.Purification by vacuum distillation 2(OCH2)]; 104.7(d, 1C, dioxanyl HC-azulene); 116.2(d, 2C, (0.5 mmHg, 140 °C) gave 4-(ethylenedioxy)cyclohexylcyclopen- azulene C1,3); 121.7(d, 2C, azulene C5,7); 134.1(d, 2C, azulene tadiene as a yellow oil, 2.5 g, 34%, dH (250 MHz, CDCl3) C4,8); 140.6(s, 2C, azulene C3a,8a); 144.7(s, 1C, azulene C6); 1.75(m, 8H, cyclohexyl CH2s); 2.30[m, 1H, cyclopentadienyl- 161.9(s, 1C, azulene C2); m/z (EI) 478 (M+, 100%).MPLC on CH(cyclohexyl)]; 2.95(m, 2H, cyclopentadiene; 3.95(m, 4H, silica gave the pure cis-2-cyclohexyl-6-(5-tridecyl-1,3-dioxan-2- ketal CH2s); 6.00–6.50(m, 3H, cyclopentadiene).yl)azulene, as purple microprisms, mp 86–87 °C (M+, calculated: 479.3882, C33H50O2 found: 479.3889); dH (250 MHz, 1-[4-(Ethylenedioxy) cyclohexyl]-6-(diethoxymethyl )azulene CD2Cl2) 0.86(t, 3H, J 7, Me); 1.1(m, 2H, cyclohexyl CH2); and 2-[4-(ethylenedioxy)cyclohexyl]-6-(diethoxymethyl )azulene 1.30(m, 22H, C11H22C2H5 ); 1.50(m, 6H, cyclohexyl); 1.80(m, 4H, cyclohexyl); 2.08(m, 1H, HC-C13H27); 2.92(m, 1H, azulene 4-(Ethylenedioxy)cyclohexylcyclopentadiene, (1.5 g, 7.28 mmol) was added to sodium hydride (0.2 g, 8.00 mmol) in THF CH-cyclohexyl); 4.09[m, 4H, 2(OCH2)]; 5.40(s, 1H, dioxanyl HC-azulene); 7.20(s, 2H, azulene H-C1,3); 7.30(d, 2H, J 10.5, (30 ml) and heated gently until the reaction had completed to give a red solution. A solution of N-butyl-4-(diethoxymethyl)- azulene H-C5,7); 8.20(d, 2H, J 10.5), azulene H-C4,8); dC (63 MHz, CD2Cl2) 14.3(q, 1C, Me), 23.1(t, 1C, CH2 ); 26.7(t, pyridinium bromide (5.0 g, 15.0 mmol) in THF (25 ml) was then added leaving a colourless solution which was heated at 1C, cyclohexyl); 27.1(t, 2C, cyclohexyl); 28.5(t, 1C, CH2); 29.7(t, 1C, CH2); 29.8[t, 7C, 7(CH2)]; 30.0(t, 1C, CH2); 30.2(t, reflux for 48 h; the reaction turning red and then dark brown. Solvent was evaporated under reduced pressure and neutral 1C, CH2); 32.3(t, 2C, cyclohexyl); 34.6(d, 1C, HC-C13H27); 40.4(d, 1C, azulene CH-cyclohexyl); 71.3[t, 2C, 2(OCH2)]; silica added to the dark brown oil.Purification by column chromatography on neutral silica using light petroleum– 105.2(d, 1C, dioxanyl HC-azulene); 116.1(d, 2C, azulene C1,3); 121.7(d, 2C, azulene C5,7); 134.1(d, 2C, azulene C4,8); 140.6(s, diethyl ether, 352, as eluent gave N-butyl-(4-ethoxycarbonyl- 4-ethyl)dihydropyridine as a colourless oil and a mixture of 2C, azulene C3a,8a); 144.7(s, 1C, azulene C6); 161.9(s, 1C, azulene C2); m/z (EI) 479 (M+, 100%).the isomers as a dark blue oil. Separation of the isomers was attempted by HPLC and reverse phase HPLC but led to 4-( Ethylenedioxy)cyclohexanol decomposition and a small amount of pure 1-[4-(ethylenedioxy) cyclohexyl]-6-(diethoxymethyl)azulene as a blue oil, 4-(Ethylenedioxy)cyclohexanone (5.0 g, 32 mmol, 1 equiv.) in (M+ Found: 370.2130, C23H30O4 calculated: 370.2144); dH dry THF (25 ml) was added dropwise to LiAlH4 (3.0 g, (250 MHz, CD2Cl2 ) 1.2 [t, 6H, J 7, 2(CH3)]; 1.85(m, 8H, 79 mmol, 2.2 equiv.) in dry THF (20 ml).When the reaction cyclohexyl); 3.23(m, 1H, azulene HC-cyclohexyl); 3.60[m, 4H, had ceased, the mixture was heated at reflux for a further 3 h 2(OCH2CH3 )]; 3.95(s, 4H, O-CH2-CH2-O); 5.4 [s, 1H, (EtO)2- and allowed to cool.Excess LiAlH4 was destroyed by the HC-azulene]; 7.25(m, 3H, azulene H-C3,5,7); 7.81(d, 1H, J 4, careful addition of wet diethyl ether and then water. The white azulene H-C2); 8.24(d, 1H, J 10, azulene H-C4); 8.33(d, 1H, J suspension was then filtered through Celite which was washed 10, azulene H-C8); dC (63 MHz, CD2Cl2) 15.3[q, 2C, with copious amounts of diethyl ether.The organic portions 2(OCH2Me)]; 32.5(t, 2C, cyclohexyl); 35.6(d, 1C, azulene CH- were combined, dried and solvent was evaporated under cyclohexyl); 62.3[t, 2C, 2(OCH2Me)]; 64.6(t, 1C, OCH2CH2- reduced pressure to leave crude 4-(ethylenedioxy)cyclohexanol O); 64.6(t, 1C, O-CH2-CH2-O); 104.9[d, 1C, (EtO)2CH-azu- as a yellow oil, 5 g, 99%, dH (250 MHz, CDCl3) 1.75(m, 8H lene]; 108.8(s, 1C, cyclohexyl-C-ketal); 117.2(d, 1C, azulene cyclohexyl CH2s); 3.80(m, 1H, HCOH); 4.00(s, 4H, ketal CH2s).C3); 120.2(d, 1C, azulene C5); 120.9(d, 1C, azulene C7); 132.5(d, 1C, azulene C2); 134.7(s, 1C, azulene C1); 135.0(d, 1C, azulene 4-( Ethylenedioxy)cyclohexyl tosylate C4); 135.9(d, 1C, azulene C8); 136.1(s, 1C, azulene C3a); 140.5(s, 1C, azulene C8a); 147.9(s, 1C, azulene C6); m/z (EI) 270 (M+, This was prepared by following the procedure of Winstein et al.12 but full experimental details are given below. 4- 50%); and 2-[4-(ethylenedioxy)cyclohexyl]-6-(diethoxymethyl)- azulene as blue microprisms, mp 53–54 °C (M+ Found: (Ethylenedioxy)cyclohexanol, (5 g, 31.6 mmol, 1 equiv.) was dissolved in dry pyridine and tosyl chloride (9.0 g, 47.2 mmol, 370.2151, C23H30O4 calculated: 370.2144); dH (250 MHz, CD2Cl2) 1.20[t, 6H, 2(OCH2Me)]; 1.80(m, 8H, cyclohexyl); 1.5 equiv.) added in small portions.The reaction mixture was stirred vigorously for 30 min and then kept at 0°C for 16 h. 2.95(m, 1H, azulene CH-cyclohexy; 3.58[m, 4H, 2(OCH2Me)]; 3.93(s, 4H, O-CH2-CH2-O); 5.42 [s, 1H, The crystals which appeared were collected and extracted into diethyl ether (50 ml).The ethereal portion was then washed (EtO)2CH-azulene]; 7.22(s, 2H, azulene H-C1,3); 7.32(d, 2H, J 10.5, azulene H-C5,7); 8.20(d, 2H, J 10, azulene H-C4,8); dC with 2 M HCl (30 ml), water (100 ml) and 10% aqueous potassium carbonate (20 ml). Solvent was evaporated under (63 MHz, CD2Cl2) 15.4[q, 2C, 2(OCH2Me)]; 31.8(t, 2C, cyclohexyl); 35.3(t, 2C, cylcohexyl); 39.1(d, 1C, azulene CH-cyclo- reduced pressure to leave a viscous oil.This was left at 0°C with seeding until crystals had formed, which were collected hexyl); 62.3[t, 2C, 2(OCH2Me)]; 64.6(t, 1C, O-CH2-CH2-O); J. Mater. Chem., 1997, 7(3), 391–401 39964.7(t, 1C, O-CH2-CH2-O); 105.0[d, 1C, (EtO)2CH-azulene]; Palladium on charcoal (75 mg) was then added and the vessel kept under an atmosphere of hydrogen.The mixture was left 108.9(s, 1C, cyclohexyl-C-ketal); 116.2(d, 2C, azulene C1,3); 122.0(d, 2C, azulene C5,7); 134.2(d, 2C, azulene C4,8); 140.5(s, stirring at 20°C until 1 equiv. of hydrogen had been taken up. The now colourless solution was filtered through Celite to 2C, azulene C3a,8a); 146.3(s, 1C, azulene C6); 160.0(s, 1C, azulene C2); m/z (EI) 370 (M+, 100%).remove the catalyst and washed with copious amounts of water. The filtrate was extracted with dichloromethane (3×60 ml) and the combined organic extracts washed with Azulene-6-carbaldehyde aq. K2CO3 (20%) and water. The organic layer was then Compound 1a (0.5 g, 2.17 mmol) was dissolved in dichloro- dried and solvent evaporated under reduced pressure to methane (100 ml) and 2 M hydrochloric acid (50 ml) added.give a slightly yellow oil which crystallised on standing. The mixture was stirred and the reaction monitored by TLC. Recrystallisation from acetone yielded 4-(4-decyloxyphenethyl)- When all the 6-(diethoxymethyl)azulene had disappeared as pyridine, as colourless crystals, 1.42 g, 94%, mp 44–45°C; dH judged by TLC, the mixture was separated and the organic (250 MHz, CDCl3) 0.90(t, 3H, Me); 1.30 [m, 14H, layer dried and the solvent evaporated under reduced pressure.CH2)2(CH2 )7Me]; 1.75 [m, 2H, CH2CH2(CH2)7Me]; 2.90(m, Recrystallisation from light petroleum gave azulene-6-carbal- 4H, CH2CH2 ); 3.90[t, 2H, CH2(CH2)8Me]; 6.75(d, 2H, dehyde as green–turquoise crystals, 0.27 g, 80%, mp 44–45 °C phenyl); 7.05(d, 2H, phenyl); 7.10(d, 2H, pyridine); 8.45(d, 2H, (M+ Found: 156.0579, C11H8O2 calculated: 156.0575); dH pyridine); dC (63 MHz, CDCl3 ) 14.1 (q, 1C, Me); 22.7(t, 1C, (250 MHz, CDCl3) 7.50(d, 2H, J 3.5, azulene H-C1,3); 7.70(d, CH2); 26.1(t, 1C, CH2); 29.3[t, 2C, (CH2)2]; 29.4(t, 2C, 2CH2 ); 2H, J 10, azulene H-C5,7); 8.10(t, 1H, J 3.5, azulene H-C2); 29.6(t, 1C, CH2); 31.9(t, 1C, CH2); 35.7(t, 1C, phenyl-CH2- 8.50(d, 2H J 10, azulene H-C4,8); 10.1 (s, 1H, CHO); dC CH2); 37.3(t, 1C, CH2-CH2-pyridine), 68.0(t, 1C, OCH2 ); (63 MHz, CDCl3) 119.8 (d, 2C, azulene C1,3); 123.7(d, 2C, 114.5(d, 2C, phenyl); 124.0(d, 2C, pyridine); 129.3(d, 2C, azulene C5,7); 135.2 (d, 2C, azulene C4,8); 137.1(s, 1C, azulene phenyl); 132.5(s, 1C, phenyl); 149.5(d, 2C, pyridine); 150.8(s, C2); 140.3(s, 2C, azulene C3a,8a); 141.7(s, 1C, azulene C6); 1C, phenyl); 157.6(s, 1C, pyridine); m/z (EI) 339 (M+, 15%). 194.6(d, 1C, CHO); m/z (EI) 156 (M+, 100%). N-Butyl-4-(4-decyloxyphenethyl )pyridinium bromide 6-(4-Hexyloxyphenethyl ) azulene, 2a 4-(4-Decyloxyphenethyl)pyridine (2.7 g, 7.96 mmol) was dis- Diethyl 4-(hexyloxybenzyl)phosphonate (1.00 g, 2.96 mmol) solved in absolute ethanol (30 ml) and 1-bromobutane (4 g, was dissolved in diethyl ether (30 ml) and potassium tert- 29.1 mmol, excess) added.The mixture was heated at reflux butoxide added (0.33 g, 2.96 mmol) to give a yellow precipitate. for 50 h and allowed to cool at which pale yellow crystals When this had dissolved azulene-6-carbaldehyde was added. appeared in the yellow solution.Excess 1-bromobutane The reaction was then kept stirring at 20°C in the dark and and ethanol were evaporated under reduced pressure and followed by TLC. After 30 min the aldehyde spot seemed drying under high vacuum then gave crude yellow crystals, to have disappeared and an upper green spot appeared. found by 1H NMR spectroscopy to be mainly N-butyl-4-(4- Purification was attempted by column chromatography on decyloxyphenethyl)pyridinium bromide, 2.26 g, 60%; dH silica using hexane–CH2Cl2, 352, as eluent in the dark to give (250 MHz, CDCl3) 0.80(t, 3H, Me); 0.95(t, 3H, Me); 1.25(m, a green crystalline product of 6-(4-hexyloxystyryl)azulene, 16H, OC2H4C7H14Me, NC2H4CH2Me); 1.75(m, 2H, which rapidly decomposed on standing, mp 225 °C (decomp.), OCH2CH2C8H17); 2.00(m, 2H, NCH2CH2C2H4); 2.95(t, 2H, dH (250 MHz, CDCl3) 0.90 (t, 3H, J 7, Me); 1.40[m, 6H, phenyl-CH2-CH2-pyridine); 3.2(t, 2H, phenyl-CH2-CH2-pyri- CH2(CH2)3Me]; 1.80(m, 2H, CH2CH2C4H9); 3.99(t, 2H, J 7, dine); 3.90(t, 2H, OCH2C9H19); 4.90(t, 2H, NCH2C3H7 ); CH2C5H11); 6.92(d, 2H, J 9, phenyl); 7.18(s, 2H, -CHNCH-); 6.75(d, 2H, phenyl); 7.00(d, 2H, phenyl); 7.80(d, 2H, pyridine); 7.32(d, 2H, J 4, azulene H-C1,3 ); 7.4(d, 2H, J 11, azulene H- 9.20(d, 2H, pyridine); m/z (EI) C27H42ON 396 (M+-Br, 50%).C5,7); 7.5(d, 2H, J 9, phenyl); 7.8(t, 1H, J 4, azulene H-C2); A less soluble product was isolated after extraction of the 8.30(d, 2H, J 11, azulene H-C4,8); m/z (EI) 330 (M+, 100%). crude yellow crystals with dry acetone, which gave cream This green product was then taken up into dry THF (30 ml) crystals, and these were determined to be pure 4-(4-decyloxy- and lithium aluminium hydride added carefully (0.2 g, phenethyl)pyridinium bromide (Found: C, 65.71; H, 7.99; N, 4.93 mmol); the mixture was heated at reflux for 3 h, then 3.43; Br, 18.89: C23H34NOBr calculated: C, 65.71; H, 8.15; N, stirred for 16 h at 20°C.An upper purple spot was observed 3.33; Br, 19.01); dH (250 MHz, CDCl3 ) 0.80(t, 3H, Me); 1.25 on TLC. The solvent was evaporated under reduced pressure (m, 14H, OC2H4C7H14Me); 1.70(m, 2H, OCH2CH2C8H17); and then purification was attempted by column chromatogra- 2.90(t, 2H, phenyl-CH2-CH2-pyridine); 3.15(t, 2H, phenyl- phy on silica, using CH2Cl2–hexane, 253, as eluent, to give 6- CH2-CH2-pyridine); 3.85(t, 2H, OCH2C9H19); 6.75(d, 2H, (4-hexyloxyphenethyl)azulene as purple microprisms, which phenyl); 6.90(d, 2H, phenyl); 7.65(d, 2H, pyridine); 8.70(d, 2H, were then recrystallised from hexane, 0.10 g, 15%, mp 105 °C; pyridine); dC (63 MHz, CDCl3) 14.1(q, 1C, Me); 22.7(t, 1C, dH (250 MHz, CDCl3 ) 0.9(t, 3H, J 7, Me); 1.3[m, 6H, CH2); 26.0(t, 1C, CH2); 29.3(t, 1C, CH2); 29.4(t, 2C, 2CH2 ); (CH2 )2(CH2)3Me]; 1.80(m, 2H, CH2CH2C4H9); 3.0(m, 4H, 29.5(t, 2C, 2CH2); 31.9(t, 1C, CH2); 35.0(t, 1C, phenyl-CH2- CH2CH2); 3.90(t, 2H, J 7, CH2C5H11); 6.7(d, 2H, J 9, phenyl); CH2); 38.3(t, 1C, CH2-CH2-pyridine); 68.1(t, 1C, OCH2 ); 7.05(d, 2H, J 11, azulene H-C5,7); 7.05(d, 2H, J 9, phenyl); 114.8(d, 2C, phenyl CH); 127.2(d, 2C, pyridine); 129.3(d, 2C, 7.30(d, 2H, J 4, azulene H-C1,3); 7.80(t, 1H, J 4, azulene H- phenyl); 130.0(s, 1C, phenyl); 140.0(d, 2C, pyridine); 158.1(s, C2); 8.20(d, 2H, J 11, azulene H-C4,8); dC (63 MHz, CDCl3); 1C, phenyl); 163.3(s, 1C, pyridine); m/z (EI) C23H34ON 340 14.0 (q, 1C, Me); 22.6(t, 1C, CH2); 25.7(t, 1C, CH2); 29.3(t, (M+-Br, 100%). 1C, CH2); 31.6(t, 1C, CH2 ); 38.0(t, 1C, CH2); 44.6(t, 1C, CH2); 68.1(t, 2C, CH2CH2); 114.5(d, 2C, phenyl); 117.9(d, 2C, azulene 6-(4-Decyloxyphenethyl) azulene, 2b C1,3); 124.1(d, 2C, phenyl); 129.4(d, 2C, azulene C5,7); 133.0(s, Freshly distilledcyclopentadiene (2.00 g, 30.3 mmol) was added 1C, phenyl); 135.8(d, 1C, azulene C2); 135.9(d, 2C, azulene dropwise over 30 min to sodium hydride (0.75 g, 24.6 mmol) C4,8); 138.9(s, 2C, azulene C3a,8a); 152.5(s, 1C, phenyl); 157.6(s, in THF (70 ml) at 0°C and the mixture was then allowed to 1C, azulene C6); m/z (EI) 332 (M+, 15%).warm to 20°C. N-Butyl-4-(4-decyloxyphenethyl)pyridinium bromide (5.36 g, 11.3 mmol) dissolved in dry THF (10 ml) was 4-(4-Decyloxyphenethyl ) pyridine then added to the pink solution which turned red, then green, then blue, and finally brown.The mixture was heated at reflux trans-4-Decyloxy-4¾-stilbazole19 (1.5 g, 4.45 mmol) was dissolved in glacial acetic acid (100 ml) to give a yellow solution. for 90 h, a blue spot being indicated by TLC. THF was 400 J. Mater. Chem., 1997, 7(3), 391–401evaporated under reduced pressure to leave a brown oil. Silica References was added to the brown oil and purification by column 1 M. R. Churchill, in Progress in Inorganic Chemistry, ed. chromatography using light petroleum (bp 40–60 °C) as eluent, S. J. Lippard, vol. 11, pp. 58–59. gave a blue product. Recrystallisation from diethyl ether– 2 E.W. Thulstrup, P. L. Case and J. Michl, Chem. Phys., 1974, 6, 410. methanol gave 6-(4-decyloxyphenethyl)azulene as blue crys- 3 K. Praefcke and D. Schmidt, Z. Naturforsch., T eil B, 1981, 34, 375. 4 T. Nozoe, S. Matsumaru, Y. Murase and S. Seto, Chem. Ind., 1955, tals, 0.64 g, 15%, mp 100°C, (Found: C, 86.55, H, 9.38; C28H36O 1257. calculated: C, 86.55; H, 9.33%); dH (250 MHz, CD2Cl2) 0.9(t, 5 R. Brettle, D. A. Dunmur, S. E. Estdale and C. M. Marson, 3H, J 7, Me); 1.3[m, 14H, (CH2)2(CH2)7Me]; 1.80(m, 2H, J. Mater. Chem., 1993, 3, 327. CH2CH2C8H17); 3.0(m, 4H, CH2CH2); 3.90(t, 2H, J 7, 6 T. Morita, K. Takase and M. Kaneko, Jpn. Pat. 0269439, 1990. CH2C9H19); 6.75(d, 2H, J 9, phenyl); 7.05(d, 2H, J 11, azulene 7 T. Morita, K. Takase and M. Kaneko, Jpn. Pat. 0269436, 1990. 8 T. Morita, K. Takase and M. Kaneko, Jpn. Pat. 0269438, 1990. H-C5,7 ); 7.05(d, 2H, J 9, phenyl); 7.30(d, 2H, J 4, azulene H- 9 T. Morita, K. Takase and M. Kaneko, Jpn. Pat. 0269437, 1990. C1,3); 7.80(t, 1H, J 4, azulene H-C2); 8.25(d, 2H, J 11, azulene 10 T. Morita, K. Takase and M. Kaneko, Jpn. Pat. 0269441, 1990. H-C4,8); dC (63 MHz, CD2Cl2); 14.3 (q, 1C, Me); 23.1(t, 1C, 11 K. Hafner, Angew. Chem., 1957, 69, 393. CH2); 26.5(t, 1C, CH2); 29.8(t, 1C, CH2); 30.0[t, 2C, (CH2)2]; 12 E. Bernaert, M. Anteumis and D. Tavernier, Bull. Soc. Chim. Belg., 32.3(t, 1C, CH2); 38.3(t, 1C, CH2); 44.9(t, 1C, CH2); 68.5(t, 1974, 83, 357. 2C, CH2CH2); 114.8(d, 2C, phenyl); 118.2(d, 2C, azulene C1,3); 13 T. Koenig, K. Rudolf, R. Chadwick, H. Geiselmann, T. Patapoff and C. E. Klopfenstein, J. Am. Chem. Soc., 1986, 108, 5024. 124.5(d, 2C, phenyl); 129.8(d, 2C, azulene C5,7); 133.5(s, 1C, 14 R. Luhowy and P. M. Keehn, J. Am. Chem. Soc., 1977, 99, 3797. phenyl); 136.1(d, 1C, azulene C2); 136.3(d, 2C, azulene C4,8); 15 K. J. Toyne, T hermotropic liquid crystals, ed. G. W. Gray, Wiley, 139.3(s, 2C, azulene C3a,8a); 153.1(s, 1C, phenyl); 158.1(s, 1C, Chichester, 1987, p. 41. azulene C6); m/z (EI) 388 (M+, 20%). 16 E. M. Averyanov, V. M. Muratov and V. G. Rumyantsev, Sov. Phys., 1985, 61, 476. 17 F. Popp and W. McEwen, J. Am. Chem. Soc., 1958, 80, 1181. 18 E. Cesarotti and H. B. Kagan, J. Organomet. Chem., 1978, 162, 297. We are grateful to Hitachi Limited for financial support, and 19 D. W. Bruce, D. A. Dunmur, E. Lalinde, P. M. Maitlis and to Dr K. Toriyama for discussion. The assistance of Dr G. P. Styring, L iq. Cryst., 1988, 3, 385. Ungar in making X-ray measurements is also gratefully acknowledged. Paper 6/06139G; Received 6th September, 1996 J. Mater. Chem., 1997, 7(3), 391–401 401