Osmotic Regulation of Betaine Content in Leymus chinensis Under Saline-alkali Stress and Cloning and Expression of Betaine Aldehyde Dehydrogenase（BADH） Gene

The potted Leymus chinensis seedlings were treated with saline-alkali solution of six different（from Ⅰ to Ⅵ） concentrations. The results demonstrate that the betaine content and Betaine-aldehyde dehydrogenase（BADH： EC 1.2.1.8） activities have a direct relation with increased stressing time in the same treatment; both exhibit a single peak with increasing the concentration of saline-alkali solution, and number V shows the highest value. The BADH gene of Leyrnus chinensis was cloned by RT-PCR and RACE technology and was designated as LcBADH. The cDNA sequence of LcBADH was 1774bp including the open reading frame（ORF） of 1521bp（coding 506 amino acids）. The vector of prokaryotic expression was constructed by inserting the LcBADH gene fragmcnt into pET30a（＋） and transformed into E. coli BL21（DE3）. The result of SDS-PAGE shows that the idio-protein with a molecular mass of 56.78 kDa was effectively expressed in the recombinant bacteria induced by isopropyl fl-D-thiogalactoside（IPTG）.     

Facile Solution-based Synthesis and Optical Properties of Co3O4 Nanoparticles at Low-temperature

Cobalt oxide（C0304） with different morphologies was achieved by a simple solution-based method. Various parallel experiments show that several experimental parameters, such as the concentrations of NaOH and ethylene glyeol（EG）, play important roles in the morphological controlling of C0304 nanoparticles. A lower concen- tration of NaOH favors quasi-spherical product with a uniform size of about 15 nm, whereas a higher concentration of NaOH generally leads to the formation of nanoplates with wide size distribution. In addition, C0304 nanorods were also obtained partially by introducing a certain amount of EG. A possible mechanism was proposed for the selective formation of C0304 with various morphologies. X-Ray diffraction（XRD）, infrared（IR） spectrometry, scanning elec- tron microscopy（SEM）, transmission electron microscopy（TEM） and UV-Vis spectrometry were used to characterize the samples.     

Immobilization and Characterization of Glucose Oxidase on Single-Walled Carbon Nanotubes and Its Application to Sensing Glucose

The negatively charged （at pH 8.2） glucose oxidase （GOx, pI ca. 4.2） was assembled onto the surface of single-walled carbon nanotubes （SWNT）, which was covered （or wrapped） by a layer of positively charged polyelectrolyte poly（dimethyldiallylammonium chloride） （PDDA）, via the electrostatic interaction forming GOx-PDDASWNT nanocomposites. Fourier transform infrared （FTIR）, UV-Vis and electrochemical impedance spectroscopy （EIS） were used to characterize the growth processes of the nanocomposites. The results indicated that GOx retained its native secondary conformational structure after it was immobilized on the surface of PDDA-SWNT. A biosensor （Nafion-GOx-PDDA-SWNT/GC） was developed by immobilization of GOx-PDDA-SWNT nanocomposites on the surface of glassy carbon （GC） electrode using Nafion （5%） as a binder. The biosensor showed the electrocatalytic activity toward the oxidation of glucose under the presence of ferrocene monocarboxylic acid （FcM） as an electroactive mediator with a good stability, reproducibility and higher biological affinity. Under an optimal condition, the biosensor could be used to detection of glucose, presenting a typical characteristic of Michaelis-Menten kinetics with the apparent Michaelis-Menten constant of KM^app ca. 4.5 mmol/L, with a linear range of the concentration of glucose from 0.5 to 5.5 mmol/L （with correlation coefficient of 0.999） and the detection limit of ca. 83 μmol/L （at a signal-to-noise ratio of 3）. Thus the biosensor was useful in sensing the glucose concentration in serum since the normal glucose concentration in blood serum was around 4.6 mmol/L. The facile procedure of immobilizing GOx used in present work would promote the developments of electrochemical research for enzymes （proteins）, biosensors, biofuel cells and other bioelectrochemical devices.     

Thermosensitive Particles with Unusual Morphology Prepared by Dispersion Copolymerization

The monodispersed polymeric particles with an unusual structure were prepared by the dispersion copolymerization of acrylonitrile/styrene（AN/St） in mixed solvents of ethanol/water by using the poly（N-isopropylacrylamide） （PNIPAAm） macromonomer as a reaction stabilizer. It was found that the AN monomer plays a key role in the formation of the particles with special morphology analyzed via scanning electron microscopy （SEM）. The reaction parameters have remarkable influences on the particle size and morphology. The particles possess a thermosensitive property according to the result of laser light scattering（LLS）.     

纳米CoHCF修饰电极的制备及其对血红蛋白的电化学测定研究

A cobalt hexacyanoferrate （CoHCF） nanoparticle （size ca. 60 nm） chemically modified electrode （CME） was fabricated and the electrochemical behavior of hemoglobin （Hb） at this nanosized CoHCF CME was studied. In comparison with a bare glassy carbon electrode （GCE） and a general CoHCF CME electrodeposited in a traditional manner, the present nanosized CoHCF CME performed efficiently electrocatalytic reduction for Hb with relatively high sensitivity, stability, and longlife, Combined with liquid chromatography （LC）, the nanosized CoHCF CME was used as the electrochemical detector of Hb in the established flow injection analysis-electrochemical determination （FIA-ECD） system. The peak current was a linear function of concentrations in the range from 2.5×10^-8 to 5.0×10^-6mol/L for Hb, with detection limit of 1.4×10^-8 mol/L. The FIA-ECD system has been successfully applied to assess the Hb content of clinic blood samples with advantages of sensitiveness, speediness, easy control and small sample-consumption.     

Theoretical Studies on the First Hyperpolarizabilities of One-dimensional Donor-bridge-acceptor Chromophores

The ground-state dipole moments and second-order nonlinear optical （NLO） properties of a series of one-dimensional （1D） chromophores with donor-bridge-acceptor （D-B-A） structures have been investigated by using the second-order MФller-Plesset （MP2） and density functional theory （DFT） methods with the basis set of 6-31＋G（d）. According to the calculated results, the relationship between the molecular static first hyperpolarizability （βμ） and the directions of electron transition has been summarized. In terms of the sign of βμ, these 1D organic chromophores were classified into two categories： type Ⅰ with negative βμ and type Ⅱ bearing positive βμ. The analyses show that the remarkable difference of the first hyperpolarizabilities between Ⅰ and Ⅱ chromophores is associated mainly with the electrostatic interaction between terminal groups and the transport electrons in excited states. Moreover, different from the popular viewpoint, the obtained results also show that most of this series of 1D D-B-A molecules are more charge-separated in the ground states than in the excited states. As a whole, this theoretical investigation, to some extent, can be considered as a useful reference in designing the NLO chromophores with large first hyperpolarizabilities.     

NOVEL HYPERBRANCHED POLY（PHENYLENE OXIDE）S WITH PHENOLIC TERMINAL GROUPS： EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.     

共振光散射成像检测5,10,15,20-四(对三甲基氨基苯)卟吩诱导的DNA超螺旋聚集体

A resonance light scattering （RLS） imaging method was proposed based on imaging and measuring the RLS features of single suprahelical species of DNA, and its appfication to DNA assay was also investigated. In acidic medium, porphine-5,10,15,20-tetrakis（p-phenyltlimethylaminium） （PTPTMA）, could stack along the molecular surface of DNA with the mode of long-range assembly to induce the formation of suprahelical species of DNA, resulting in strong RLS signals in the range of 450-510 nm. Under the excitation of 488 nm fight beam of argon ion laser source, single suprahelical species could be observed with the aid of a common microscope due to the strong scattered fight emitted by the suprahelical species. By capturing the RLS images of the single suprahelical species with a cooled charge coupled device （CCD） camera, and analyzing the RLS data, herein an RLS imaging method of DNA was proposed based on the linear relationship between the counts of suprahelical species in the detection focus plane and the concentration of DNA in nanograms. When 1.8 μmol/L PTPTMA was employed, both calf thymus DNA （ct DNA） and fish sperm DNA （fs DNA） in the range of 25-1100 ng/mL could be detected with the limits of detection lower than 25 ng/mL （3a）. Four synthetic samples were detected satisfactorily with relative standard deviations less than 5.1%.     

Synthesis of TiO2/ZnSn（OH）6 Hollow Nano-composite via a Simultaneous Crystallization-etching Route as Photocatalyst

We report the synthesis of TiO2/ZnSn（OH）6 as a novel nano-composite material via a simultaneous crystallization-etching route with cubic nano-ZnSn（OH）6 and TiF4 as the precursors. The structure, composition and morphology of the composite were characterized by XRD, EDS, FETEM and FESEM, which showed the prepared TiO2/ZnSn（OH）6 had a unique morphology of hollow cubic nano-ZnSn（OH）6 attached with rutile TiO2 nanoparticles. The results of photocatalytic activity measurement indicated the photocatalytic activity of the prepared composite was better than that of nano-ZnSn（OH）6. This study may be helpful for the design and fabrication of functional comoosite materials.     

环糊精与两种有机物的包合物的不同光解特性

The effectiveness of the solubilization and photodegradation of β-cyclodextrin （β-CD） and hydroxypropyl-β- cyclodextrin （HPCD） on two hydrophobic organic compounds （HOC） of methyl parathion and pentachlorophenol was investigated. The results indicate that the solubilization or photodegradation of two HOC were influenced by complexing with β-CD or HPCD. The solubility of pentachlorophenol （PCP） was increased linearly with β-CD concentration. The solubility of methyl parathion （MPT） was increased with the increase of β-CD concentration initially, however, as the β-CD concentration was enhanced above 3 g/L, the solubility was decreased with increase of β-CD concentration. The solubilities of two HOC were increased linearly with the increase of HPCD concentration. Although the photodegradation of MPT was improved, the photodegradation of PCP was restrained by complexation of HOC with β-CD or HPCD. In a word, the effectiveness of photodegradation or solubilization of HPCD was more significant than that of β-CD. One potential application of such a method was the in situ remediation of hydrophobic organic pollutants in contaminated soil and groundwater or industrial waste streams.     

Enzyme‐Mediated Preparation of (+)‐ and (−)‐β‐Irone and (+)‐ and (−)‐cis‐γ‐Irone from Irone alpha®

The (−)‐ and (+)‐β‐irones ((−)‐ and (+)‐ 2 , resp.), contaminated with ca. 7 – 9% of the (+)‐ and (−)‐trans‐α‐isomer, respectively, were obtained from racemic α‐irone via the 2,6‐trans‐epoxide (±)‐ 4 (Scheme 2). Relevant steps in the sequence were the LiAlH₄ reduction of the latter, to provide the diastereoisomeric‐4,5‐dihydro‐5‐hydroxy‐trans‐α‐irols (±)‐ 6 and (±)‐ 7 , resolved into the enantiomers by lipase‐PS‐mediated acetylation with vinyl acetate. The enantiomerically pure allylic acetate esters (+)‐ and (−)‐ 8 and (+)‐ and (−)‐ 9 , upon treatment with POCl₃/pyridine, were converted to the β‐irol acetate derivatives (+)‐ and (−)‐ 10 , and (+)‐ and (−)‐ 11 , respectively, eventually providing the desired ketones (+)‐ and (−)‐ 2 by base hydrolysis and MnO₂ oxidation. The 2,6‐cis‐epoxide (±)‐ 5 provided the 4,5‐dihydro‐4‐hydroxy‐cis‐α‐irols (±)‐ 13 and (±)‐ 14 in a 3 : 1 mixture with the isomeric 5‐hydroxy derivatives (±)‐ 15 and (±)‐ 16 on hydride treatment (Scheme 1). The POCl₃/pyridine treatment of the enantiomerically pure allylic acetate esters, obtained by enzymic resolution of (±)‐ 13 and (±)‐ 14 , provided enantiomerically pure cis‐α‐irol acetate esters, from which ketones (+)‐ and (−)‐ 22 were prepared (Scheme 4). The same materials were obtained from the (9S) alcohols (+)‐ 13 and (−)‐ 14 , treated first with MnO₂, then with POCl₃/pyridine (Scheme 4). Conversely, the dehydration with POCl₃/pyridine of the enantiomerically pure 2,6‐cis‐5‐hydroxy derivatives obtained from (±)‐ 15 and (±)‐ 16 gave rise to a mixture in which the γ‐irol acetates 25a and 25b and 26a and 26b prevailed over the α‐ and β‐isomers (Scheme 5). The (+)‐ and (−)‐cis‐γ‐irones ((+)‐ and (−)‐ 3 , resp.) were obtained from the latter mixture by a sequence involving as the key step the photochemical isomerization of the α‐double bond to the γ‐double bond. External panel olfactory evaluation assigned to (+)‐β‐irone ((+)‐ 2 ) and to (−)‐cis‐γ‐irone ((−)‐ 3 ) the strongest character and the possibility to be used as dry‐down note.     

Diastereoselective Electrophilic Amination of Chiral 1‐Benzoyl‐2,3,5,6‐tetrahydro‐3‐methyl‐2‐(1‐methylethyl)pyrimidin‐4(1H)‐one for the Asymmetric Syntheses of α‐Substituted α,β‐Diaminopropanoic Acids

The chiral compounds (R)‐ and (S)‐1‐benzoyl‐2,3,5,6‐tetrahydro‐3‐methyl‐2‐(1‐methylethyl)pyrimidin‐4(1H)‐one ((R)‐ and (S)‐ 1 ), derived from (R)‐ and (S)‐asparagine, respectively, were used as convenient starting materials for the preparation of the enantiomerically pure α‐alkylated (alkyl=Me, Et, Bn) α,β‐diamino acids (R)‐ and (S)‐ 11 – 13 . The chiral lithium enolates of (R)‐ and (S)‐ 1 were first alkylated, and the resulting diasteroisomeric products 5 – 7 were aminated with ‘di(tert‐butyl) azodicarboxylate’ (DBAD), giving rise to the diastereoisomerically pure (≥98%) compounds 8 – 10 . The target compounds (R)‐ and (S)‐ 11 – 13 could then be obtained in good yields and high purities by a hydrolysis/hydrogenolysis/hydrolysis sequence.     

Analogues of α‐Campholenal (= (1R)‐2,2,3‐Trimethylcyclopent‐3‐ene‐1‐acetaldehyde) as Building Blocks for (+)‐β‐Necrodol (= (1S,3S)‐2,2,3‐Trimethyl‐4‐methylenecyclopentanemethanol) and Sandalwood‐like Alcohols

To complete our panorama in structure–activity relationships (SARs) of sandalwood‐like alcohols derived from analogues of α‐campholenal (= (1R)‐2,2,3‐trimethylcyclopent‐3‐ene‐1‐acetaldehyde), we isomerized the epoxy‐isopropyl‐apopinene (?)‐ 2d to the corresponding unreported α‐campholenal analogue (+)‐ 4d (Scheme 1). Derived from the known 3‐demethyl‐α‐campholenal (+)‐ 4a , we prepared the saturated analogue (+)‐ 5a by hydrogenation, while the heterocyclic aldehyde (+)‐ 5b was obtained via a Bayer‐Villiger reaction from the known methyl ketone (+)‐ 6 . Oxidative hydroboration of the known α‐campholenal acetal (?)‐ 8b allowed, after subsequent oxidation of alcohol (+)‐ 9b to ketone (+)‐ 10 , and appropriate alkyl Grignard reaction, access to the 3,4‐disubstituted analogues (+)‐ 4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)‐ 4b or its methyl ketone (+)‐ 4h , afforded stereoselectively the trans‐epoxy derivatives 11a,b , while the minor cis‐stereoisomer (+)‐ 12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C₂ or C₃ side chain). Alternatively, the corresponding trans‐epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans‐epoxy aldehyde (+)‐ 11a or by stereoselective epoxidation of the α‐campholenol (+)‐ 15a or of its acetate (?)‐ 15b , respectively. Their cis‐analogues were prepared starting from (+)‐ 12a . Either (+)‐ 4h or (?)‐ 11b , was submitted to a Bayer‐Villiger oxidation to afford acetate (?)‐ 16a . Since isomerizations of (?)‐ 16 lead preferentially to β‐campholene isomers, we followed a known procedure for the isomerization of (?)‐epoxyverbenone (?)‐ 2e to the norcampholenal analogue (+)‐ 19a . Reduction and subsequent protection afforded the silyl ether (?)‐ 19c , which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)‐ 20c . Further oxidation and epimerization furnished the trans‐ketone (?)‐ 17a , a known intermediate of either (+)‐β‐necrodol (= (+)‐(1S,3S)‐2,2,3‐trimethyl‐4‐methylenecyclopentanemethanol; 17c ) or (+)‐(Z)‐lancifolol (= (1S,3R,4Z)‐2,2,3‐trimethyl‐4‐(4‐methylpent‐3‐enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)‐ 4b gave the saturated cis‐aldehyde (+)‐ 21 , readily reduced to its corresponding alcohol (+)‐ 22a . Similarly, hydrogenation of β‐campholenol (= 2,3,3‐trimethylcyclopent‐1‐ene‐1‐ethanol) gave access via the cis‐alcohol rac‐ 23a , to the cis‐aldehyde rac‐ 24 .     

Atropselective Dibrominations of a 1,1′‐Disubstituted 2,2′‐Biindolyl with Diverging Point‐to‐Axial Asymmetric Inductions. Deriving 2,2′‐Biindolyl‐3,3′‐diphosphane Ligands for Asymmetric Catalysis

On the ¹H NMR timescale, 2,2′‐biindolyls with (R)‐configured (1‐alkoxyprop)‐2‐yl, (1‐hydroxyprop)‐2‐yl, or (1‐siloxyprop)‐2‐yl substituents at C‐1 and C‐1′ are atropisomerically stable at <0 °C and interconvert at >30 °C. A 2,2′‐biindolyl (R,R)‐ 17 a of that kind and achiral (!) brominating reagents gave the atropisomerically stable 3,3′‐dibromobiindolyls (M)‐ and/or (P)‐ 18 a at best atropselectively—because of point‐to‐axial asymmetric inductions—and atropdivergently, exhibiting up to 95 % (M)‐ and as much (P)‐atropselectivity. This route to atropisomerically pure biaryls is novel and should extend to other substrates and/or different functionalizations. The dibromobiindolyls (M)‐ and (P)‐ 18 a furnished the biindolyldiphosphanes (M)‐ and (P)‐ 14 without atropisomerization. These syntheses did not require the resolution of a racemic mixture, which distinguishes them from virtually all biaryldiphosphane syntheses known to date. (M)‐ and (P)‐ 14 acted as ligands in catalytic asymmetric allylations and hydrogenations. Remarkably, the β‐ketoester rac‐ 25 c was hydrogenated trans‐selectively with 98 % ee; this included a dynamic kinetic resolution.     

Enantioselective Access to (−)‐Ambrox® Starting from β‐Farnesene

Starting from inexpensive (E)‐β‐farnesene ( 1 ), an eight‐step enantioselective synthesis of the olfactively precious Ambrox^® ((?)‐ 2a ) has been performed. The crucial step is the catalytic asymmetric isomerization of (2E,6E)‐N,N‐diethylfarnesylamine ( 3 ) to the corresponding enamine (?)‐(R,E)‐ 4a , applying Takasago's well‐known industrial methodology. The resulting dihydrofarnesal ((+)‐(R)‐ 5 ) (90% yield, 96% ee), obtained after in situ hydrolysis (AcOH, H₂O), was then cyclized under catalytic SnCl₄ conditions, via its corresponding unreported enol acetate (?)‐(R)‐ 4b , to afford trans‐decalenic aldehyde (+)‐ 6a . Subsequent transformations furnished bicyclic ketone (?)‐ 8a and unsaturated nitrile (+)‐ 11 , both reported as intermediates to access to (?)‐ 2a .     

Asymmetric Catalysis with a Phosphoramidite Derived from (−)‐(aR)‐ [1,1′‐Binaphthalene]‐8,8′‐diol

Treatment of (aR)‐[1,1′binaphthalene]‐8,8′‐diol ((−)‐ 1 ) with hexamethylphosphorous triamide afforded the N,N‐dimethylphosphoramidite (−)‐ 3 (Scheme 1). The synthesis of the analogous N,N‐diisopropylphosphoramidite 4 failed, however, and afforded the acyclic phosphonamidate (−)‐ 5 . The application of the cyclic phosphoramidite (−)‐ 3 towards asymmetric catalysis was investigated. The borane reduction of acetophenone ( 6 ) to (R)‐1‐phenylethanol ( 7 ) in the presence of (−)‐ 3 proceeded with 96% ee (Scheme 2). The use of (−)‐ 3 as ligand in several Cu‐catalyzed addition and substitution reactions resulted in enantioselectivities ranging from 0 to 50% (Schemes 3 and 4).     

Synthesis of (P)‐ and (M)‐6,7‐Bis[(diphenylphosphanyl)methyl]‐8,12‐diphenylbenzo[a]heptalenes – Potential Ligands for Homogeneous Asymmetric Catalysis

The title bis(phosphane) ligands have been prepared starting from optically pure diisopropyl (P)‐ and (M)‐8,12‐diphenylbenzo[a]heptalene‐6,7‐dicarboxylates ((P)‐ 1b and (M)‐ 1b ) that had been obtained by HPLC separation of rac‐ 1b on a semi‐preparative Chiralcel OD column. Reduction of (P)‐ 1b and (M)‐ 1b with diisobutylaluminum hydride (DIBAH) gave optically pure (P)‐ and (M)‐dimethanols 3 (Scheme 6 and Fig. 5). Unfortunately, the almost quantitative chlorination of rac‐ 3 with PCl₅ in CHCl₃ at −60° led with (M)‐ 3 to nearly complete loss of optical integrity. However, mesylate formation of (P)‐ 3 , followed by phosphanylation with LiP(BH₃)Ph₂ gave (P)‐ 6 with only a small loss of optical activity. Optically pure (P)‐ 6 was obtained by crystallization from Et₂O/hexane, which removed the nearly insoluble rac‐ 6 . The pure bis(phosphane) ligands (P)‐ 2 and (M)‐ 2 can be liberated quantitatively from 6 by warming 6 in toluene in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO). First Rh^I‐catalyzed asymmetric hydrogenation reactions of (Z)‐α‐(acetamido)cinnamic acid ((Z)‐ 14 ) in the presence of (P)‐ 2 led to (R)‐N‐acetylphenylalanin ((R)‐ 15 ) in optical purities up to 77% (see Table 1).     

Annulenoide Tetrathiafulvalene:, 5,16‐Bis(1,3‐benzodithiol‐2‐yliden)‐5,16‐dihydrotetraepoxy‐ und 5,16‐Bis(1,3‐benzodithiol‐2‐yliden)‐5,16‐dihydrotetraepithio[22]annulene(2.1.2.1)

Annulenoid Tetrathiafulvalenes: 5,16‐Bis(1,3‐benzodithiol‐2‐ylidene)‐5,16‐dihydrotetraepoxy‐ and 5,16‐Bis(1,3‐benzodithiol‐2‐ylidene)‐5,16‐dihydrotetraepithio[22]annulenes(2.1.2.1) The title compounds are among the first tetrathiafulvalenes with annulene spacers, here with tetraepoxy‐[22]annulene(2.1.2.1) (see 3a ), tetraepithio[22]annulene(2.1.2.1) (see 3b ), and diepithiodiepoxy[22]annulene(2.1.2.1) (see 23 ) units. The annulenoid tetrathiafulvalenes 3a and 3b are prepared by cyclizing McMurry coupling of the 5,5′‐(1,3‐benzodithiol‐2‐ylidenemethylene)bis[furan‐ or thiophene‐2‐carbaldehydes] ( 8a or 8b , resp.) or by Wittig reaction of (1,3‐benzodithiol‐2‐yl)tributylphosphonium tetrafluoroborate ( 13b ) with tetraepoxy[22]annulene(2.1.2.1)‐1,12‐dione 20 (formation of 3a ) or diepithiodiepoxy[22]annulene(2.1.2.1)‐1,12‐dione 22 (formation of 23 ). The annulenoide tetrathiafulvalene 3a is obtained as a mixture of the isomers (E,E)‐ and (Z,Z)‐ 3a . At 130°, (Z,Z)‐ 3a rearranges quantitatively into the (E,E)‐isomer. Isomer (E,E)‐ 3a is a dynamic molecule, where the (E)‐ethene‐1,2‐diyl bridges rotate around the adjacent σ‐bonds. The tetraepithioannulene derivative 3b as well as 23 only exist in the (Z,Z)‐configuration. The oxidation of (E,E/Z,Z)‐ 3a with Br₂ yields the annulene‐bridged tetrathiafulvalene dication (E,E)‐ 3a _Ox, while with 4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile (DDQ) obviously only the radical cation 3a _Sem is formed, which belongs to the class of cyanine‐like violenes. The annulenoide tetrathiafulvalenes 3b and 23 , which exist only in the (Z,Z)‐configuration, obviously for steric reasons, cannot be oxidized by DDQ. Electrochemical studies are in agreement with these results.     

Quinolone Analogs 13: Synthesis of Novel 1,1′‐(2‐Methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) and Related Compounds

The reaction of the 4‐hydroxyquinoline‐3‐carboxylate 6 with pentaerythritol tribromide gave the 1,1′‐(2‐methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 11 , whose reaction with bromine afforded the 1,1′‐(2‐bromo‐2‐bromomethylpropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 12 . Compound 12 was transformed into the (Z)‐1,1′‐(2‐acetoxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 13 or (E)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylate) 14 . Hydrolysis of the dimer (Z)‐ 13 or (E)‐ 14 with potassium hydroxide provided the (E)‐1,1′‐(2‐hydroxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylic acid) 15 or (Z)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylic acid) 16 , respectively. The nuclear Overhauser effect (NOE) spectral data supported that those hydrolysis resulted in the geometrical conversion of (Z)‐ 13 into (E)‐ 15 or (E)‐ 14 into (Z)‐ 16 .     

Unexpected Thermal Transformation of Aryl 3‐Arylprop‐2‐ynoates: Formation of 3‐(Diarylmethylidene)‐2,3‐dihydrofuran‐2‐ones

A number of aryl 3‐arylprop‐2‐ynoates 3 has been prepared (cf. Table 1 and Schemes 3 – 5). In contrast to aryl prop‐2‐ynoates and but‐2‐ynoates, 3‐arylprop‐2‐ynoates 3 (with the exception of 3b ) do not undergo, by flash vacuum pyrolysis (FVP), rearrangement to corresponding cyclohepta[b]furan‐2(2H)‐ones 2 (cf. Schemes 1 and 2). On melting, however, or in solution at temperatures >150°, the compounds 3 are converted stereospecifically to the dimers 3‐[(Z)‐diarylmethylidene]‐2,3‐dihydrofuran‐2‐ones (Z)‐ 11 and the cyclic anhydrides 12 of 1,4‐diarylnaphthalene‐2,3‐dicarboxylic acids, which also represent dimers of 3 , formed by loss of one molecule of the corresponding phenol from the aryloxy part (cf. Scheme 6). Small amounts of diaryl naphthalene‐2,3‐dicarboxylates 13 accompanied the product types (Z)‐ 11 and 12 , when the thermal transformation of 3 was performed in the molten state or at high concentration of 3 in solution (cf. Tables 2 and 4). The structure of the dihydrofuranone (Z)‐ 11c was established by an X‐ray crystal‐structure analysis (Fig. 1). The structures of the dihydrofuranones 11 and the cyclic anhydrides 12 indicate that the 3‐arylprop‐2‐ynoates 3 , on heating, must undergo an aryl O→C(3) migration leading to a reactive intermediate, which attacks a second molecule of 3 , finally under formation of (Z)‐ 11 or 12 . Formation of the diaryl dicarboxylates 13 , on the other hand, are the result of the well‐known thermal Diels‐Alder‐type dimerization of 3 without rearrangement (cf. Scheme 7). At low concentration of 3 in decalin, the decrease of 3 follows up to ca. 20% conversion first‐order kinetics (cf. Table 5), which is in agreement with a monomolecular rearrangement of 3 . Moreover, heating the highly reactive 2,4,6‐trimethylphenyl 3‐(4‐nitrophenyl)prop‐2‐ynonate ( 3f ) in the presence of a twofold molar amount of the much less reactive phenyl 3‐(4‐nitrophenyl)prop‐2‐ynonate ( 3g ) led, beside (Z)‐ 11f , to the cross products (Z)‐ 11fg , and, due to subsequent thermal isomerization, (E)‐ 11fg (cf. Scheme 10), the structures of which indicated that they were composed, as expected, of rearranged 3f and structurally unaltered 3g . Finally, thermal transposition of [¹⁷O]‐ 3i with the ¹⁷O‐label at the aryloxy group gave (Z)‐ and (E)‐[¹⁷O₂]‐ 11i with the ¹⁷O‐label of rearranged [¹⁷O]‐ 3i specifically at the oxo group of the two isomeric dihydrofuranones (cf. Scheme 8), indicating a highly ordered cyclic transition state of the aryl O→C(3) migration (cf. Scheme 9).