Aconapelsulfonines A and B,seco C20-diterpenoid alkaloids deriving via Criegee rearrangements of napelline skeleton from Aconitum carmichaelii

Two sulfo nated seco C₂₀-diterpenoid alkaloids,aconapelsulfonines A(1) and B(2),were isolated from an aqueous extract of the raw material of "Fu Zi"(the Aconitum carmichaelii lateral roots),of which the structures were elucidated by various spectroscopic data,combined with X-ray crystallogra phic analysis.The unprecedented skeletons are biogenetically proposed to be derived via Criegee rearrangements of the napelline-type architecture.The two compounds exhibited dose-depended analgesic activities on an acetic acid-induced mice writhing test.     

A new C27-steroidal glycoside from Ophiopogon japonicus

A new C27-steroidal glycoside with three known compounds were isolated from the tuber of Ophiopogonjaponicus （Thunb.） Ker-Gawl. Based on the spectral analysis, including HRMS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC, their chemical structures were determined as pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-xylopyranosyl-（1→ 4）-13-D-gluco- pyranoside （1）, pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-glucopyranoside （2）, ophiopojaponin C （3） and ophiopogonin D （4）. 2007 Jian Zhong Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

In plane and out of plane anisotropy in Langmuir-Blodgett films of discogenic molecules

Langmuir-Blodgett films of a discotic mesogenic pyrylium tetrafluoroborate salt (1) have been investigated from the point of view of their in-plane anisotropy, i.e. considering the average molecular orientation with respect to the dipping direction. The molecules are found to stand on edge with their flat polycyclic core more or less perpendicular to the dipping direction. Mixing 1 with N(C₄H₉)₄⁺ TCNQ^- in the spreading solvent leads to a different behaviour of the monolayer at the air-water interface, involving the formation of the Pyrylium-TCNQ salt. In contrast to the films of pure 1, these films do not exhibit any in-plane anisotropy after deposition on a solid substrate. The temperature dependance of the molecular anisotropy of both films has also been investigated. The results are presented and discussed in the framework of their mesomorphic properties together with the influence of the anion associated with Pyrylium.     

Mesogenic behaviour of (4-alkoxybenzylideneamino)bromobenzene, (4-alkoxybenzylideneamino)benzenethiols, and thiolatonickel complexes of the thiols

The synthesis, characterization and mesogenic properties of Schiff base compounds arising from the reaction of 4-alkoxybenzaldehydes with 4-aminothiophenol or 4-bromoaniline are described. Whereas the Schiff base thiol with two benzene rings in the molecule, HSC₆H₄NC(H)C₆H₄OC₁₆H₃₃ (2), is non-mesogenic, the bromo analogue, BrC₆H₄NC(H)C₆H₄OC₁₆H₃₃ (3), is mesogenic. The introduction of a third benzene ring into the molecular architecture of 2 and 3 produced thiol- and bromo-Schiff base compounds, HSC₆H₄NC(H)C₆H₄OC(O)C₆H₄OC₁₆H₃₃ and BrC₆H₄NC(H)C₆H₄OC(O)C₆H₄OC₁₆H₃₃, respectively, that are both mesogenic. The thiol compounds react with nickelocene to form [(η ⁵-C₅H₅)Ni(μ ₂-SC₆H₄NC(H)C₆H₄OC₁₆H₃₃)]₂ and [(η ⁵-C₅H₅)Ni(μ ₂-SC₆H₄NC(H)C₆H₄OC(O)-C₆H₄OC₁₆H₃₃)]₂, but the nickel complexes are not mesogenic.     

CPI induction of liquid crystal behaviour in triphenylenes with a mixture of hydrophobic and hydrophilic side chains

2,3,6,7,10,11-Hexasubstituted triphenylenes have been synthesized that contain a mixture of hydrophobic (C₆H₁₃O) and hydrophilic (CH₃OCH₂CH₂OCH₂CH₂O) side chains. At one extreme HAT6 (1a) (six hydrophobic chains) shows thermotropic behaviour and at the other TP6EO2M (1e) (six hydrophilic chains) shows lyotropic behaviour. Of the triphenylenes with a mixture of hydrophobic and hydrophilic side chains, only the triphenylene with one hydrophilic side chain and five hydrophobic side chains (1b) gives a thermotropic columnar phase. None of the others show liquid crystal behaviour. However, all of these triphenylenes form binary 1:1 compounds when mixed with PDQ9 (2a) and with PTP9 (2b). These CPI (complimentary polytopic interaction) stabilized compounds give thermotropic hexagonal columnar phases over wide temperature ranges.     

Two new steroidal glycosides from Ophiopogon japonicus

Two new C27-steroidal glycosides were isolated from the fibrous roots of Ophiopogon japonicus. The spectral analysis and chemical evidence revealed their chemical structures to be （25R）-spirost-5,14-dien-3β-yl-O-α-L-rhamnopyranosyl-（1 → 2）-β-D- xylopyranosyl-（1 → 4）-β-D-glucopyranoside （1） and ophiogenin 3-O-β-D-glucopyranoside （2）.     

Anionic Cyclization Approach to Hexahydrobenzo[b] furan-3-one and Hexahydro-1H-3-indolone:Application to Total Syntheses of Natural Products

Hexahydrobenzo[b]furan-3-one(3) and hexahydro-1H-3-indolone (4) are potentially useful intermediates for total synthesis of natural products, such as the hexahydrobenzofuran unit (5) of avermectins and pancracine (6). Anionic cyclization approach toward (3) and (4) have been developed. Their application to the total synthesis of (5) and (6) will be presented.     

6,6-Di-C-alkyl-d-galactopyranoses. A new group of liquid crystalline compounds forming columnar phases [1]

The geminally C-branched 6,6-di-C-n-alkyl-d-galactopyranoses 3a-d prepared in two steps from 1,2:3,4-di-O-isopropylidene-d-galacturonic acid methylester 1 and the even numbered C₈-C₁₂-alkylmagnesium bromides, represent a new group of 'double tailed' thermotropic mesogens forming columnar supramolecular structures based on hydrogen bridged (disc-like) multimers in accordance with the hypothesis of the Praefcke group. Furthermore, the thermal behaviour of the homologous 6-O-alkyl-d-galactopyranoses 4a-e is discussed in connection with the revised model for the molecular arrangement in smectic A phases of 'single tailed' carbohydrates.     

The synthesis and liquid crystalline behaviour of alkoxy-substituted derivatives of 1,4-bis(phenylethynyl)benzene

Despite the prevalence of organised 1,4-bis(phenylethynyl)benzene derivatives in molecular electronics, the interest in the photophysics of these systems and the common occurrence of phenylethynyl moeties in molecules that exhibit liquid crystalline phases, the phase behaviour of simple alkoxy-substituted 1,4-bis(phenylethynyl)benzene derivatives has not yet been described. Two series of 1,4-bis(phenylethynyl)benzene derivatives, i.e. 1-[(4'-alkoxy)phenylethynyl]-4-(phenylethynyl)benzenes (5a-5f) and methyl 4-[(4'-alkoxy)phenylethynyl-4'-(phenylethynyl)] benzoates (18a-18f) [alkoxy = n-C₄H₉ (a), n-C₆H₁₃ (b), n-C₉H₁₉ (c), n-C₁₂H₂₅ (d), n-C₁₄H₂₉ (e), n-C₁₆H₃₃ (f)] have been prepared and characterised. Both series have good chemical stability at temperatures up to 210°C, the derivatives featuring the methyl ester head-group (18a-18f) offering rather higher melting points and generally stabilising a more diverse range of mesophases at higher temperatures than those found for the simpler compounds (5a-5f). Smectic phases are stabilised by the longer alkoxy substituents, whereas for short and intermediate chain lengths of the simpler system (5a-5c) nematic phases dominate. Diffraction analysis was used to identify the SmB_hex phase in (5d-5f) that is stable within a temperature range of approximately 120-140°C. The relationships between the organisation of molecules within these moderate temperature liquid crystalline phases and other self-organised states (e.g. Langmuir-Blodgett films) remain to be explored.     

Preparation of silybin 23-esters ability against LPO and and evaluation of their inhibitory DNA protective properties

Twelve 23-esterified silybin derivatives with different patterns of substituents such as aromatic and aliphatic groups (1-12) were designed and synthesized. The antioxidative properties of these compounds were evaluated. The modified silybin analogues exhibited improved inhibitory effects against rat liver homogenate lipid peroxidation compared to silybin, with exception of the trimethoxylated ester (5) and the aliphatic one (9). Compounds 3, 5, 7, 8 and 11 displayed their protective properties on DNA cleavage in a dose-dependent manner.     

5＇-Hydroxyzearalenol,a new β-resorcylic macrolide from Fusarium sp. 05ABR26

A new β-resorcylic macrolide, 5＇-hydroxyzearalenol （1）, was isolated from the culture broth of a marine-derived fungus Fusarium sp. 05ABR26. Three known compounds, zearalenone （2）, 8＇-hydroxyzearalenone （3） and zearalenol （4） were also isolated. The structure and relative stereochemistry of 1 were elucidated on the basis of spectroscopic data and single-crystal X-ray diffraction data. Compound 2 displayed potent inhibitory activity against Pyricularia oryzae with a MIC value of 6.25 μg/mL, while compound 3 was much less active; however, 1 and 4 showed no obvious activity.     

Crystal-smectic E mesophases in a series of 2-(4-n-alkylphenyl)indenes

A series of 2-(4-n-alkylphenyl)indenes (3) with different alkyl substituents (CH₃ to C₁₀H₂₁) were synthesized and systematically characterized using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction compared with 2-phenylindene (3a). Depending on the alkyl chain length, highly ordered crystal-smectic E mesophases were observed and confirmed by X-ray diffraction for the derivatives 3h-3k with heptyl to decyl chains (n = 6-9). For 3f with a pentyl side chain (n = 4), an X-ray crystal structure analysis was carried out.     

A Novel Cyclization of Squalene Initiated by Radical Cation

Squalene 1 is recognized as the precursor of sterols and polycyclic triterpenoids that play important roles in numerous life processes¹. In view of the fact that the cyclization of hexa-1, 5-diene by γ-irradiation² and some isoprenoid polyenes by photochemical method³ through radical cation intermediates have been reported and that tris (p-bromophenyl)ammoniumyl hexachloroantimonate (TBPA⁺SbCl₆, 2) could oxidize olfines to the corresponding radical cations that underwent pericyclic reactions⁴, we thought it might be worthwhile to try the biomimetic cyclization of squalene initiated by radical cations. Previously we⁵ have reported the cyclization of geraniol and nerol to cis-p-mentha-2,8-dien-l-ol by reaction with 2. Herein, we report the cyclization of 1 initiated by 2 in dry dichloromethane to give 20-R-protosta-5,24-diene 3a and 20-S-protosta-5,24-diene 3b in the ratio of 1:1 with the total yield of 20%(Scheme 1).     

Synthesis of 14-epi-19-nor-22-oxa-1α,25-dihydroxyvitamin D3

The synthesis of 14-epi-19-nor-22-oxa-1α,25（OH）2D3 5 was started from diol 8 via Fall＇s method, oxidation, epimerization, protection, coupling with the 19-nor-A-ring 7, and then deprotection of the hydroxyl functions.     

Recent Progress in the Synthetic Applications of Substituted Furans and Pyrroles

In this lecture, I would like to present efficient synthetic routes towards the total synthesis of syringolide 1 (2)^1,2 and secosyrin 1 (3),¹ employing 2,4-disubstituted furan 1 as a common precursor. A modified total synthesis of prehispanolone (6)³ from (S)-(+)-Wieland-Miescher ketone (4) via hispanolone (5) will also be discussed. Our methodology for the synthesis of 3,4-disubstituted-lH-pyrroles⁴ and for the generation of 3,4-didehydrothiophene⁵ has also guided us to the successful identification of 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (7),which is presumably the most strained heterocyclic cumulene ever recorded.     

A new series of nematic and smectic liquid crystals with negative dielectric anisotropy: the effect of terminal chain substitution on thermal and electro-optical properties

Two alkyl (1b and 1c) and four fluoroalkyl derivatives (1d-1f) of 4-arylbutyric acid (1c, 1d and 1e) and 4-arylbutanol (1b, 1f and 1g) [aryl = 2',3'-difluoro-4'-(2-(E-4-pentylcyclohexyl)ethyl)-biphenyl-1-yl] were prepared and investigated in the pure form as nematic materials (1b and 1c) and as additives to a ferroelectric liquid crystal (FLC) host (1d-1f). A comparison of 1b and 1c with the decyl analogue 1a demonstrates the effect of terminal chain modification on thermal and electro-optical properties. The substitution of the -CH₂O- (1b) or -COO- (1c) for -CH₂CH₂- in 1a destabilized the N and SmA phases or completely eliminated the smectic behaviour (1c). Dielectric analysis revealed that the chain modification increased the negative Δε, reduced elastic constant K ₁₁ and moderately decreased rotational viscosity γ₁. The temperature dependence of the key electro-optical parameters was analysed for ester 2, the methyl analogue of 1c, which exhibits a 45 K wide N phase. All four fluoroalkyl derivatives 1d-1f showed enantiotropic SmA phases and 1e also exhibited a monotropic SmC phase. Solutions of 1d-1f in a FLC host (0.2 mmol g^-1) increased the tilt angle Θ (up to 45° for 1g), reduced rotational viscosity γ₁ and the risetime τ. The most dramatic changes were observed for 1g, which contains 15 fluorine atoms.     

Synthesis and characterisation of main-chain hydrogen-bonded supramolecular liquid crystalline complexes formed by azo-containing compounds

A series of azopyridine-containing hydrogen bonding acceptors (4a-c) with flexible spacers of oligo(methylene) were synthesised. Hydrogen-bonded polymeric complexes 4/5 and trimeric complexes 4/6₂ , where 5 and 6 are aromatic dicarboxylic acids and monocarboxylic acids, respectively, were prepared and their liquid crystallinity was examined using differential scanning calorimetry and polarising optical microscopy. The study showed that most of the complexes displayed reversible thermotropic nematic phase. The isotropic to nematic phase transition temperatures of polymeric complexes 4/5 and trimeric complexes 4/6₂ in general decreased with the increase in length of spacers and terminal groups in the corresponding proton acceptors 4 and the proton donors 5 and 6, respectively. Hydrogen bonding interactions in complexes 4/5 and 4/6₂ were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.     

Synthesis and characterization of new liquid crystalline materials containing a non-activated arylazoindolinobenzospiropyranyl group as a chiral unit. Part II

Two series of new liquid crystalline compounds containing a non-activated arylazoindolinobenzospiropyran, ABP-SPAB 1a-1e (series 1) and SPAP-ABPC 2a-2e (series 2), have been synthesized. These LC dyes were characterized by a differential scanning calorimetry polarizing optical microscopy, X-ray diffraction and electro-optical measurements. All but one of the series 1 compounds examined exhibit monotropic second and/or third transition liquid crystal phases on cooling from the isotropic liquid. In particular, ABP-SPAB 1b shows a monotropic SmC phase, in addition to a SmA phase. In series 2, most of the compounds exhibit a monotropic nematic phase on cooling. SPAP-ABPC 2c forms an enantiotropic nematic phase and a monotropic SmA phase; 2e shows enantiotropic nematic and SmA phases.     

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

Two kinds of monocyclic troponoid mesogens, 2,5-dialkanoyloxytropones (4) and 5-alkanoyloxy2-alkoxytropones (5), were prepared. The former showed monotropic smectic A phases and the virtual isotropic liquid-smectic A transitions of the latter were determined by extrapolation of results in a binary phase diagram. Comparing the mesogenic properties between the tropones 4 and the 2-alkanoyloxy-5-alkoxytropones (1), the alkanoyloxy group at C-5 enhances both the melting points and the transition temperatures of the smectic A phases. From the comparison between 5 and 1 , the alkanoyloxy group at C-2 lowers the melting points.     

Novel Enone-benzene Rearrangement of 4,4-Dialkylcholest-5-en-3-ones to Ring-B Aromatic Steroidal Hydrocarbons Catalysed by p-Toluenesulfonic acid

Under acidic conditions, α,α-dimethyl-β,γ-unsaturated cyclohexanones undergoes an enone-benzene rearrangement leading to aromatic derivatives^1-4. We recently run an enone-benzene rearrangement of 4,4-dimethyl-cholest-5-en-3-one (1a) catalysed by montmorillonite K-10 to give 1,3,4-trimethyl-19-norcholesta-1,3,5(10)-triene (2a) in moderate yield accompanying intractable mixture of hydrocarbons as by products⁵. Repetition of this reaction by employing TsOH as a catalyst, 2a was obtained in 65% yield and a new product, 6-methyl-3-isopropyl-A,19-dinorcholesta-6,8,10(5)-triene (3a), was also isolated in 25% yield. The formation of 3a has not been reported in earlier studies^1-5. Herein we report the novel enone-benzene rearrangement of 4,4-dialkylcholest-5-en-3-ones (1a~d) leading to ring-B aromatic steroidal hydrocarbons (3a~d) catalysed by TsOH (Scheme 1).