醌型木素模型物的光学特性

为探索醌型木素化学结构与颜色的关系,以五种醌型木素模型物2-甲氧基-1,4-苯醌(I)、1,2-苯醌(II)、4-亚烯丙基-2-甲氧基-2,5-环己二烯酮(亚甲基醌)(III)、5-甲氧基-1,4-苯醌-2-氧负离子(IV)和5-甲基-1,4-苯醌-2-氧负离子(V)作为纸浆中醌型木素发色体的代表,在B3LYP/6-311++G(2d,p)水平上获得了它们在乙醇中的稳定基态构型,采用含时密度泛函理论(TD-DFT)在同等水平上计算了其在乙醇溶液中的电子光谱,并分析了它们在可见光范围内的吸收.结果发现:五种模型物在可见光范围内的吸收均源于电子的π→π*跃迁,它们的最大吸收波长顺序依次为IIIIIIIVV,吸光系数顺序依次为IVIVIIIII;漂白过程中生成的醌氧负离子以及邻醌类模型物具有中等大小的吸光系数(ε=1978-3197),吸收波长较长(445.47-552.36 nm),是漂白后纸浆具有颜色的重要原因.对醌类模型物吸收波长较小(414.91 nm),吸光系数大小为中等(ε=2094),亚甲基醌类模型物虽然吸光系数大(ε=31935),但吸收波长较小(407.90 nm),二者对漂白后纸浆的颜色影响较小.     

Synthesis of mimosamycin

Mimosamycin (1) was synthesized in eight steps with an overall yield of 13% from 2-methoxy-3-methyl-1,4-benzoquinone by regioselective introduction of a chloromethyl group at C-6 and a methoxycarbonylmethyl group at C-5 and subsequent reaction of the intermediate methyl (o-(chloromethyl)phenyl)acetate derivative 16 with methylamine. Oxidation of the 5,7,8-trimethoxy-2,6-dimethyl-1, 4-dihydroisoquinoline-3(2H)-one 17 thus obtained, using cerium(IV) ammonium nitrate as a selective oxidizing agent, gave mimosamycin (1) in good overall yield.     

A new hydroquinone diglucoside from <Emphasis Type="Italic">Lysimachia fordiana</Emphasis>

A new hydroquinone diglucoside along with five known compounds was isolated from the whole plant of Lysimachia fordiana Oliv. The structure of the new compound was determined to be 2-heptyl-6-methoxy-1,4-hydroquinone-1,4-di-O--D-glucopyranoside (6). The five known compounds were identified as pentacosane (1), stigmasterol (2), 2-heptyl-6-methoxy-1,4-benzoquinone (3), palmitic acid (4), and rutin (5), respectively. This is the first report of the isolation of Lysimachia fordiana Oliv. in the family Primulaceae.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 377–379, September–October, 2004.     

A new alkylated benzoquinone from rhizomes of Iris kumaonensis

A novel alkylated unsaturated p-benzoquinone designated as 3-[(z)-12'-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone was isolated from hexane extract of the rhizomes of Iris kumaonensis and it's structure was confirmed by extensive spectroscopic analysis, IR, MS, HREIMS, 1D, 2D NMR and comparison with the literature data of known compounds.     

Metal carbonyl derivatives of sulfur-containing quinones and hydroquinones: synthesis, structures, and electrochemical properties

The reaction of CpMoMn(mu-S(2))(CO)(5), 1, with 1,4-benzoquinone in the presence of irradiation with visible light yielded the quinonedithiolato complex CpMoMn(CO)(5)(mu-S(2)C(6)H(2)O(2)), 2. The new complex CpMoMn(CO)(5)(mu-S(2)C(6)Cl(2)O(2)) (4) was synthesized similarly from 1 and 2,3-dichloro-1,4-benzoquinone. Compounds 2 and 4 were reduced with hydrogen to yield the hydroquinone complexes CpMoMn(CO)(5)[mu-S(2)C(6)H(2)(OH)(2)], 3, and CpMoMn(CO)(5)[mu-S(2)C(6)Cl(2)(OH)(2)], 5. UV-vis irradiation of solutions of Fe(2)(CO)(6)(mu-S(2)) and 1,4-benzoquinone yielded the hydroquinone complex Fe(2)(CO)(6)[mu-S(2)C(6)H(2)(OH)(2)], 6. Compound 6 was oxidized to the quinone complex Fe(2)(CO)(6)(mu-S(2)C(6)H(2)O(2)), 7, by using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Substitution of the CO ligands on 6 by PPh(3) yielded the derivatives Fe(2)(CO)(5)(PPh(3))[mu-S(2)C(6)H(2)(OH)(2)], 8, and Fe(2)(CO)(4)(PPh(3))(2)[mu-S(2)C(6)H(2)(OH)(2)], 9. The electrochemical properties of 3, 5, 6, 8, and 9 were measured by cyclic voltammetry. The molecular structure of each of the new compounds 2-9 was established by single-crystal X-ray diffraction analyses.     

Carbazoledioxazines having long alkyl groups 1. Synthesis of carbazoledioxazines with linear type structure

Carbazoledioxazines with linear type structure (5,15-dialkyl-8,18-dichloro-5,15-dihydrodiindolo[3,2-b:-3′,2′-m]triphenodioxazine) were selectively synthesized by demethanolation ring closure of 2,5-bis(2-methoxy-9-alkyl-3-carbazolylamino)-3,6-dichloro-1,4-benzoquinone in a high boiling solvent. The structure has been confirmed by ¹H-nmr and X-ray crystallography.     

Metal carbonyl derivatives of 1,4-quinone and 1,4-hydroquinone

CpMoMn(CO)5(mu-S2), 1 reacts with 1,4-benzoquinone to yield CpMoMn(CO)5(mu-S2C6H2O2), 2 containing a 1,4-quinonedithiolato ligand formed by replacing two of the hydrogen atoms on one of the C-C double bonds of 1,4-benzoquinone with sulfur atoms from the disulfido ligand in 1. Compound 2 was reduced with hydrogen to yield CpMoMn(CO)5[mu-S2C6H2(OH)2], 3 which contains a 1,4-hydroquinonedithiolato ligand. Compound 3 was reoxidized to 2 with ferrocenium hexafluorophosphate.     

Photoinduced self-substitution of haloquinones

A series of novel oligo(halobenzoquinoid) compounds have been obtained from the photoinduced self-substitution of 2,5-dibromo-1,4-benzoquinone (1a), 2,6-dibromo-1,4-benzoquinone (1b), 2-chloro-1,4-benzoquinone (1c), 2-bromo-5-chloro-1,4-benzoquinone (1d), 2,3,5,6-tetrachloro-1,4-benzoquinone (1e) and 1,4-benzoquinone (1f) in the presence of N,N-dimethyl-t-butylamine (2) in acetonitrile. Dimers, trimers and/or pentamers of these haloquinones were found to be the major products.     

Palladium (II) Assisted Preparation of Methoxyarylbenzoquinones

The reaction of 2-methoxy-1,4-benzoquinone with methoxyphenolic derivative compounds obtained from wood tar constituents, assisted by palladium (II) acetate in acetic acid, allowed the preparation of five novel methoxyaryl-substituted 1,4-benzoquinones, as well as four structural isomer mixtures.     

A 5-methylthiopenicillin analog and its transformation to novel bicyclic β-lactams

Reaction of methoxyacetyl chloride with 2-methylthio-2-thiazoline resulted in the stereoselective production of one isomer of 6-methoxy-5-methylthiopenam which underwent rearrangement to 6-methoxy-7-methylthio-5-oxo-2,3,4,5-tetrahydro-1,4-thiazepine when treated with trifluoroacetic acid. Subsequent thioamidation and alkylation with methyl iodide provided 5,7-bismethylthio-6-methoxy-2,3-dihydro-1,4-thiazepine which reacted with methoxyacetyl chloride and triethylamine to give a novel 1,4-thiazabicyclo[5.2.0]non-5-ene. Other substituted bicyclic β-lactams of similar structure have also been synthesized.     

Synthesis of aromatic polyesters and polyamides by alternating copolymerizations of 1,4-dicarbonyl-1,4-dihydronaphthalene with bezoquinones and benzoquinone diimines

1,4-Dicarbonyl-1,4-dihydronaphthalene ( 1 ) was synthesized by the dehydrochlorination reaction of 1,4-dihydronaphthalene-1,4-dicarbonyl chloride with triethylamine and obtained as its very dilute solution, but it easily polymerized in the concentration as high as 0.1 mol/L to give its polymer. 1 generated in situ by the dehydrochlorination reaction of 1,4-dihydronaphthalene-1,4-dicarbonyl chloride in a deoxygenated toluene polymerized alternatingly with benzoquinones such as 2-dodecylthio-p-benzoquinone, 2,5-di(tert-butyl)-p-benzoquinone, p-benzoquinone, and 2,3-dichloro-5,6-dicyano-p-benzoquinone, and with benzoquinone diimines such as N,N′-diethoxycarbonyl-p-benzoquinone diimine, N,N′-dibenzoyl-p-benzoquinone diimine, and N,N′-diphenyl-p-benzoquinone diimine to give aromatic polyesters and polyamides, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1929–1936, 1998     

Reaction of 1,4-benzoquinones with PH-phosphonium salts

A novel approach has been proposed to the synthesis of phosphonium salts containing a 1,4-dihydroxybenzo fragment via reaction of 2-methyl-1,4-benzoquinone or 2-isopropyl-5-methyl-1,4-benzoquinone with PH-phosphonium salts generated in situ from triphenylphosphine and trifluoromethanesulfonic or trifluoroacetic acid. The structure of the synthesized phosphonium salts was determined by NMR spectroscopy and X-ray analysis.     

Synthetic transformations of higher terpenoids: XXVIII. Diels-Alder reactions of 16-(trimethylsiloxybutadienyl) labdanoids

15,16-Epoxy-16-(3-trimethylsiloxybuta-1,3-dien-1-yl)labdanoids were synthesized, and their reactions with cyclic dienophiles (1,4-benzoquinone, 1,4-toluquinone, 2-bromo-6-methyl-1,4-benzoquinone, and N-methylmaleimide) were studied. The reactions with unsymmetrically substituted benzoquinones were not selective. Methods for the preparation of hybrid compounds containing furan diterpenoid and substituted naphthoquinone, octahydroisoindoletrione, or hexahydroisoindoledione fragments were proposed.     

A novel series of copolymers containing 2,5-dicyano-1,4-phenylene-vinylene--synthetic tuning of the HOMO and LUMO energy levels of conjugated polymers

A series of copolymers of 2,5-dicyano-1,4-phenylenevinylene and 2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene were synthesized by Wittig reaction. The HOMO and LUMO energy levels of copolymers can be easily tuned by controlling the feed ratio of co-monomers.     

An investigation of oxidative animation of 2-methyl-1,4-benzoquinone with pyrrolidine

Oxidative amination of 2-methyl-1,4-benzoquinone with pyrrolidine yielded 2-methyl-6-pyrrolidino-1,4-benzoquinone as the major product along with 2-methyl-5-pyrrolidino-1,4-benzoquinone formed as the minor product. No detectable amount of 2-methyl-3,6-bis-(pyrrolidino)-1,4-benzoquinone was observed.     

Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime ethers: XIII. Specificity of bromination of N-Acetyl(aroyl)-1,4-benzoquinone monoimines

6-Hydroxy-2-methyl(aryl)-1,3-benzoxazoles were synthesized by bromination of N-acetyl(aroyl)-1,4-benzoquinone monoimines.     

利用Diels-Alder反应构建桉烷类倍半萜骨架关键中间体的研究

以3-甲基-1,3-间苯二酚和异戊醛为原料分别合成亲双烯2-甲氧基-6-甲基对苯醌和双烯1-甲氧基-3-异丙基-1,3-丁二烯,通过Diels-Alder反应,高区域选择性地得到桉烷类倍半萜骨架中间体2c.     

Synthetic Approach Towards Hexaprismane. A Novel Entry to Homosecohexaprismane Skeleton by Cage Enlargement

A series of caged 1,4-diols, 26, 29a/29b, 31 , were synthesized from the Diels-Alder cycloadduct 21 of 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene and 1,4-benzoquinone. Reduction of enedione 21 with aqueous TiCl₃, followed by base-catalyzed enolization in the presence of acetic anhydride, gave diene 23b , which reacted with maleic anhydride and 1,4-benzoquinone to produce the corresponding [4+2] cycloadducts 24b and 27 , respectively. The adduct 24b was converted to birdcaged 1,4-diol 26 by photocyclization followed by decarboxylative olefination of resulted caged anhydride 25b . The adduct 27 was photocyclized to cage compound 28 , which was aromatized to dihydroquinone 29a by acid-catalyzed enolization, or benzo-annulated compound 31 by reduction and dehydration. The birdcaged 1,4-diols 26 and 31 underwent fragmentation induced by (diacetoxyiodo)benzene to give enediones 38/39 and 41/42 , respectively. Photocyclization of 38 and 39 produced the corresponding caged compounds 43 and 44 , respectively, possessing homosecohexaprismane skeletons. The corresponding monohydrate 43a of 43 was structurally characterized by single-crystal X-ray diffraction.     

In situ synthesis, photometric and spectroscopic studies of chelating system during the 1,4,7,10,13,16-hexaoxacyclooctadecane charge transfer reaction with different acceptors

Electron donor acceptor complexes (EDA) of the 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) as a rich donor were spectrophotometrically discussed and synthesized in solid form according the interactions with different nine of usual π-acceptors like 2,3,5,6-tetrachlorocyclohexa-2,5-diene-1,4-dione (p-chloranil; p-CHL), tetrachloro-1,2-benzoquinone (o-chloranil; o-CHL), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoquinodimethane (TCNQ), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid; CLA), N-bromosuccinimide (NBS), 2,4,6-trinitrophenol (picric acid; PA). Spectroscopic and physical data such as formation constant (K(CT)), molar extinction coefficient (?(CT)), standard free energy (ΔG°), oscillator strength (f), transition dipole moment (μ), resonance energy (R(N)) and ionization potential (I(p)) were estimated in chloroform or methanol at 25°C. Based on the elemental analysis and photometric titrations the CT-complexes were formed indicated the formation of 1:1 charge-transfer complexes for the o-CHL, TCNQ, DCQ, DBQ and NBS acceptors but 1:3 ratio for p-CHL, DDQ, CLA and PA, respectively. The charge-transfer interactions were interpretative according to the formation of dative ion pairs [18C6(?+), A(?-)], where A is acceptor. All of the resulting charge transfer complexes were isolated in amorphous form and the complexes formations on IR and (1)H NMR spectra were discussed.     

Synthesis of 2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl Naphthalene: A Product from the Isomerisation of Diels-Alder Adducts of Both 5-Methyl- and 6-Methyl-2-acetyl-1,4-benzoquinone with 1,3-Butadiene

2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl-naphthalene was synthesised via Diels-Alder addition of 2-acetyl-3-methyl-1,4-benzoquinone to buta-1,3-diene followed by enolisation. It was identical with material obtained by pyridine-induced acetyl migration from the 1,3-butadiene adducts of both 3- and 6-methyl-2-acetyl-1,4-benzoquinone.