Structural determination of flavonoids from Sophora flavescens

Eight flavonoids were isolated from Sophora flavescens. Among them, three prenylflavanones: (2S)-6[2(3-hydroxyisopropyl)-5-methyl-4-hexenyl]-5-methoxy-7,2', 4'-trihydroxyflavanone (1), (2S)-5, 4'-dimethoxy-8-lavandulyl-7, 2'-dihydroxy flavanone (2) and (2S)-8-(5-hydroxy-2-isopropenyl-5-methylhexyl)-7-methoxy-5,2', 4'-trihydroxyflavanone (3) are new compounds. Their chemical structures were determined by spectral methods including 2D NMR.     

NMR assignments of unusual flavonoids from the kino of Eucalyptus citriodora

Two unusual flavonoids, 3,5,4',5'-tetrahydroxy-7-methoxy-6-[1-(p-hydroxy-phenyl)ethyl]flavanone (1) and 3,5,7,4',5'-pentahydroxy-6-[1-(p-hydroxy-phenyl)ethyl] flavanone (2), were isolated from the kino of Eucalyptus citriodora. Structural elucidation of the new compounds were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences ((1)H, (1)H-COSY, HMQC, HMBC).     

1H and 13C NMR assignments for two new xanthones from the endophytic fungus Xylaria sp. FRR 5657

The complete 1H and 13C NMR assignments are reported for the new natural products, 7-hydroxy-3-(hydroxymethyl)-1-methoxy-9H-xanthen-9-one (1) and 2,5-dihydroxy-8-methoxy-6-methyl-9-oxo-9H-xanthene -1-carboxylic acid (2). Both of these secondary metabolites were isolated from the fermentation culture of the endophytic fungus Xylaria sp. FRR 5657. 1D and 2D NMR experiments that included 1H, gCOSY, gHSQC and gHMBC were used for the determination of the structure and assignment of these xanthones.     

Synthesis and dehydration reaction of 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydronaphth-2-ol: possible intermediate of Lasofoxifene

The paper deals with a simple and sufficient synthesis of key precursor of Lasofoxifene. The 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene was prepared by a sequence of five reactions steps: first 1-(4-benzyloxyphenyl)-6-methoxy-3,4-dihydronaphthalene was prepared (70%), and this was quantitatively epoxidized to 7b-[4-(benzyloxy)phenyl]-5-methoxy-1a,2,3,7b-tetrahydronaphtho[1,2-b]oxirene. Catalytic (ZnI₂) isomerization of the epoxide gave 1-(4-benzyloxyphenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalen-2-one (75%). Its subsequent reaction with phenylmagnesium bromide gave 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydro-2-naphthol (87%). Acid-catalysed dehydration of this alcohol by polyphosphoric acid (25°C) provides 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,4-dihydronaphthalene (80%). Dehydration in the system of acetic anhydride/polyphosphoric acid gives 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene (66%).     

Complete assignments 1H and 13C NMR spectral data of four anabaseine derivatives

The anabaseine derivatives 6-methoxy-7-hydroxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, 6,7-dimethoxy-1-(pyridin-3-yl)-1,2,3,4-tetrahydroisoquinoline and 6,7-dimethoxy-1-(piperidin-3-yl)-1,2,3,4-tetrahydroisoquino- line were prepared either by demethylation with HBr or by reduction with different reagents, NaBH4 and H2/PtO2 from 6,7-dimethoxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, as starting material. The structures have been fully assigned by the combination of one- and two-dimensional experiments.     

Structure elucidation of two new xanthone derivatives from the marine fungus Penicillium sp. (ZZF 32#) from the South China Sea

Two new xanthones, 8-(methoxycarbonyl)-1-hydroxy-9-oxo-9H-xanthene-3-carboxylic acid (1) and dimethyl 8-methoxy-9-oxo-9H-xanthene-1,6-dicarboxylate (2) and one known xanthone methyl 8-hydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylate (3) were isolated from the culture broth of the mangrove fungus Penicillium sp. (ZZF 32#) collected from the South China Sea. Their structures were established by comprehensive analysis of one-dimensional (1D) and two-dimensional (2D) NMR data. The structure of compound 3 was confirmed by X-ray crystallography, which led to the suggestion that janthinone (4) might have the same structure as 3. Compounds 1-3 were inactive against KB or KBv200 cells during cytotoxicity evaluations.     

Ab initio and experimental studies on the hetero-Diels-Alder and cheletropic additions of sulfur dioxide to (E)-1-methoxybutadiene: a mechanism involving three molecules of SO(2)

Kinetics on the cheletropic addition of sulfur dioxide to (E)-1-methoxybutadiene (1) to give the corresponding sulfolene 2 (2-methoxy-2,5-dihydrothiophene-1,1-dioxide) gave the rate law d[2]/dt = k[1][SO(2)](x)() with x = 2.6 +/- 0.2 at 198 K. Under these conditions, no sultine 3 [(2RS,6RS)-6-methoxy-3,6-dihydro-1,2-oxathiin-2-oxide] resulting from a hetero-Diels-Alder addition was observed, and the cheletropic elimination 2 --> 1 + SO(2) did not occur. Ab initio and DFT quantum calculations confirmed that the cheletropic addition 1 + SO(2) --> 2 follows two parallel mechanisms, one involving two molecules of SO(2) and the transition structure with DeltaG(++) = 18.2 +/- 0.2 kcal/mol at 198 K (exptl); 22.5-22.7 kcal/mol [B3LYP/6-31G(d,p)], the other one involving three molecules of SO(2) with DeltaG(++) = 18.9 +/- 0.1 kcal/mol at 198 K (exptl); 19.7 kcal/mol [B3LYP/6-31G(d,p)]. The mechanism involving only one molecule of SO(2) in the transition structure requires a higher activation energy, DeltaG(++) = 25.2 kcal/mol [B3LYP/6-31G(d,p)]. Comparison of the geometries and energetics of the structures involved into the 1 + SO(2) --> 2, 3 and 1 + 2SO(2) --> 2, 3 + SO(2) reactions obtained by ab initio and DFT methods suggest that the latter calculation techniques can be used to study the cycloadditions of sulfur dioxide. The calculations predict that the hetero-Diels-Alder addition 1 + SO(2) --> 3 also prefers a mechanism in which three molecules of SO(2) are involved in the cycloaddition transition structure. At 198 K and in SO(2) solutions, the entropy cost (TDeltaS(++)) is overcompensated by the specific solvation by SO(2) in the transition structures of both the cheletropic and hetero-Diels-Alder reactions of (E)-1-methoxybutadiene with SO(2).     

Zur Struktur der Tetrahydro-4-phenylspiro([1]benzopyran-2,4′(1′H)-pyrimidin)-2′(3′H)-one bzw.-thione über Heterocyclen, 49. Mitt

The structures of tetrahydro-4-phenylspiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-ones and-thiones4 a, b resp., are proved by synthesis. 3-(2-methoxy-3,5-dimethylphenyl)-3-phenylpropionic acid11 b is prepared from 3,4-dihydro-6,8-dimethyl-4-phenylcoumarin10. The lithium salt of11 b reacts with isobutenyl-lithium to 1-(2-methoxy-3,5-dimethylphenyl)-5-methyl-1-phenyl-4-hexen-3-on12 a. 12 a is transferred with urea in acid medium and NH₄CNS resp. in a mixture of dihydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyl]-4,4-dimethyl-2(1H)-pyrimidinone and-thione13 a, b and tetrahydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyliden]-4,4-dimethyl-2(1H)-pyrimidinone and-thione14 a, b resp.14 b leads to13 a, b with H₂O₂. Heating of13 a, 14 a and14 b resp. with pyridin-HCl leads to the spiro compounds4 a, b.     

天然产物的绝对构型研究(Ⅰ)——通过比较旋光和碳谱的实验值与计算值确定酮类、内酯类和醇类化合物的绝对构型

在研究天然产物绝对构型的过程中, 筛选了系列绝对构型未鉴定的化合物, 在B3LYP/aug-cc-pVDZ//B3LYP/6-31G(d)水平上计算了它们的旋光和碳谱数据. 结果表明, 计算结果与实验数值十分符合, 从而鉴定出了这些化合物的绝对构型. 另外, 根据计算结果和早期实验报告更正了1个化合物的碳谱化学位移.     

Addition-Rearrangement of Aryl- and Alkoxysulfonyl Isocyanates with 5-Methyl-Substituted 3,4-Dihydro-2-methoxy-2H-pyrans. Selective Synthesis of Functionalized 2-Piperidones(1)

3,4-Dihydro-2-methoxy-5-methyl-2H-pyran and 3,4-dihydro-2-methoxy-5,6-dimethyl-2H-pyran undergo addition-rearrangement reactions with arylsulfonyl isocyanates to generate the corresponding 3-formyl- and 3-acetyl-6-methoxy-3-methyl-1-(arylsulfonyl)-2-piperidones. For example, 3,4-dihydro-2-methoxy-5-methyl-2H-pyran and phenylsulfonyl isocyanate afforded 3-formyl-6-methoxy-3-methyl-1-(phenylsulfonyl)-2-piperidone as a separable trans/cis mixture in high yield. The more reactive phenoxysulfonyl and alkoxysulfonyl isocyanates provided analogous results.     

Polyketides from a marine sponge-derived fungus Mycelia sterilia and proton-proton long-range coupling

A series of polyketide-originated metabolites (1-5) were isolated from a marine sponge-derived fungus Mycelia sterilia. Of these, 1-3 were new compounds. Their structures were elucidated by spectroscopic methods as (4R*, 5S*, 6S*, 8S*, 13R*)-1-(2,8-dihydroxy-1,2,6-trimethyl-1,2,6,7,8,8a-hexahydro-naphthalen-1-yl)-3-methoxy-propan-1-one (1), 4,8-dihydroxy-7-(2-hydroxy-ethyl)-6-methoxy-3,4-dihydro-2H-naphthalen-1-one (2) and 1-methyl-naphthalene-2,6-dicarboxylic acid (3). In 1, the proton-proton long-range coupling phenomenon claimed attention and was discussed.     

Ultrafiltration and Pyrolysis Gas Chromatography Mass Spectrometry of Chlorolignins in Pulp Mill Effluent

Abstract

Investigations on the effluent of a German pulp mill on the river Rhine using ultrafiltration and pyrolysis gas chromatography mass spectrometry have shown the presence of several chlorinated 2-methoxyphenols, which probably originate from chlorinated lignin or lignosulfic acid. Chlorinated phenolic pyrolysis products identified were 2-methoxy-6-chlorophenol, 2-methoxy-4-methyl-6-chlorophenol, 2-methoxy-dichlorophenol, 2-methoxy-4-vinyl-6-chlorophenol, 2-methoxy-4-(chloropropyl)phenol, 2-methoxy-4-(prop-2-enyl)-6-chlorophenol, 2-methoxy-4-(propan-2-one)-6-chlorophenol, 2-methoxy-3, 5, 6-trichlorophenol, 2-methoxy-4-vinyl-3, 5, 6-trichlorophenol. Monochlorinated 2-methoxyphenols were the dominant chlorinated pyrolysis products, smaller amounts of di- and trichloromethoxyphenols were also detected. 2-Methoxyphenols (guaiacols) were the dominant lignin pyrolysis products, only small amounts of 2, 6-dimethoxyphenols (syringols) were detected. This indicates the origin from soft wood. A Py-(GC)-(MS)-TIC-chromatogram of reference spruce milled wood lignin is comparable with the TIC-chromatogram of pulp mill effluent MW-fraction > 10,000, showing many similar compounds. The ultrafiltration fraction 1000 < MW < 10,000 showed a remarkably empty TIC-chromatogram, with 2-methoxyphenol and 2-methoxy-6-chlorophenol as the only significant phenolic peaks. This may indicate a high degree of oxidation/chlorination of lignin in this fraction.     

Cyclization of 2-methoxy-6-(substituted benzyloxy)acetophenone hydrazones in the presence of polyphosphoric acid(PPA)

Cyclization of 2-methoxy-6-benzyloxy acetophenone hydrazone gave 3-methyl-4-meth-oxy indazole and 3-methyl-4-methoxy-7-benzyl indazole in the presence of polyphosphoric acid(PPA).The hydrazone was probably converted to 2-hydroxy-6-methoxy acetophenone hydra-zone and 2-hydroxy-3-benzyl-6-methoxy acetophenone hydrazone followed by cyclization to thecorresponding indazoles in acidic conditions.Cyelization of 2-methoxy-6-(halo or alkyl or arylbenzyloxy)acetophenone hydrazones gave similar products.Cyclization of 2-methoxy-6-(p-nitrobenzyloxy)acetophenone hydrazone gave 2-(p-nitrophenyl)-3-methyl-4-methoxy benzo-furan and 3-methyl-4-methoxy indazole while 2-methoxy-6-(m-nitrobenzyloxy)acetophenonehydrazone gave 3-methyl-4-methoxy indazole,3-methyl-4-methoxy-7-(m-nitrophenyl)indazole and3-methyl-4-(m-nitrobenzyloxy)indazole.     

Investigations of intramolecular hydrogen bonding in three types of Schiff bases by 2H and 3H NMR isotope effects

Hydrogen bonding within the structures of three Schiff bases (1-3), obtained by condensation of 4-methoxy-, 5-methoxy- and 4,6-dimethoxysalicylaldehyde with methylamine, was investigated by measuring deuterium and tritium NMR isotope effects. The primary deuterium and tritium isotope effects (delta(XH)-delta(XD/T)) and secondary one-bond nitrogen deuterium effect appear to be very useful parameters for defining the character of intramolecular hydrogen bonds. The tritium isotope effects were also determined for nitrogen-hydrogen one-bond coupling constants for both 4-methoxy and 4,6-dimethoxy derivatives. These parameters are seen to be highly sensitive to hydrogen bond characteristics and can be used to distinguish localized and tautomeric hydrogen bonds.     

A PGSE diffusion and electrophoretic NMR study of Cs+ and Na+ dynamics in aqueous crown ether systems

Multinuclear pulsed gradient spin-echo (PGSE) NMR diffusion and linewidth measurements were used to probe binding and transport in aqueous Na+-15-crown-5, Na+-18-crown-6, Cs+-15-crown-5 and Cs+-18-crown-6 systems. Since direct PGSE observation of many alkali cations is precluded by either low inherent sensitivity or rapid relaxation (or both), the feasibility of proton-detected electrophoretic NMR (ENMR) measurements to complement PGSE data was investigated. ENMR measurements were performed on aqueous Cs+-, Li+-, Na+-, K+-, and Rb+- 18-crown-6 systems. The data analysis is based on a two-site binding model and its corresponding association constants. Cs+ was found to bind considerably more tightly to 18-crown-6 (K=8 M-1) than to 15-crown-5 (K approximately 2 M-1), whereas Na+ had almost equal affinity (K approximately 4.5 M-1) for 15-crown-5 and 18-crown-6. The difficulties encountered in analysing the NMR parameters, methodological limitations and the implied need for more complicated binding models are discussed.     

Calix[4] crowns with Methoxynaphthoylmethyl Pendant Groups

The novel calix [4] crowns with two pendant groups were prepared by the alkylation of calix 141 crowns with 6-methoxy-2-bromoacetylnaphthalene. ^1H NMR titration and picrate extraction experiments indicated that they exhibit higher complexing efficiency than their parent compounds and possess obvious selectivity for Na^ or K^ , respetively, and that the cation is encapsulated inside the preorganized ionophoric cavity defined by carbonyl oxygens, the crown ether and the phenoxy oxygens.From UV and fluorescent spectra it is revealed that calix [4]crown-4 3a with 6-methoxy-2-naphthoylmethyl pedant groups exhibits remarkable cation-induced photophysical effects and it could be utilized as a selective fluorescent sensor for Ca^2 .     

(1)H and (13)C NMR assignments for five anthraquinones from the mangrove endophytic fungus Halorosellinia sp. (No. 1403)

We report the unambiguous assignments of the (1)H and (13)C NMR spectra of two new natural products, namely, 1,4,5,6,7,9-hexahydroxy-2-methoxy-7-methyl-5beta,9beta,8abeta, 6alpha,10aalpha-hexahydroanthracen-10 (10aH)-one (1) and 1,4,6-trihydroxy-2-methoxy-7-methylanthracene-9, 10-dione (2), together with three known anthraquinones. These compounds were all isolated from the marine endophytic fungus No. 1403 collected from the South China Sea. Compounds 3 and 4 were isolated from the marine fungus for the first time. The structures were elucidated by the spectroscopic methods 1D and 2D NMR including COSY, HMQC, HMBC and NOE, and HREIMS. In our cytotoxicity assays, compound 5 showed cytotoxicity toward KB and KBv-200 cells with IC(50) of 1.40 and 2.58 microg/ml, respectively. In addition, the plausible biogenic relationship of compounds 1, 2, 3 and 4 is discussed.     

Optical absorption of methoxy and carboethoxy derivatives of 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline

Paper deals with experimental investigations and quantum chemical calculations of the optical absorption spectra of methoxy and carboethoxy 1,3-diphenyl derivatives of the pyrazoloquinoline ([PQ]): 6-methoxy-1,3-dyphenil-[PQ], 6-methoxy-1,3-(p-methoxyphenyl)-[PQ], 6-methoxy-1-(p-methoxyphenyl)-[PQ] and 6-carboethoxy-1,3-diphenyl-[PQ]. The quantum chemical calculations are performed by means of the semiempirical quantum chemical methods (AM1 or PM3) applied to: (a) the equilibrium molecular conformation in vacuo (T=0 K); (b) the molecular dynamic (MD) trajectory (T=300 K) which includes the dynamics of a certain molecular fragment (moiety) only (fragmental MD simulations); or (c) the MD trajectory obtained for most general case within the total MD simulations at T=300 K. The results of these calculations are compared with the measured spectra of the optical absorption. The quantum chemical simulations show that the dynamics of the methoxy or carboethoxy groups practically does not influence the absorption spectrum whereas the strongest its modification (300相似文献   

Synthesis and total assignment of 1H and 13C NMR spectra of new oxoisoaporphines by long-range heteronuclear correlations

The new oxoisoaporphines 7H-dibenzo[de,h]quinolin-7-one, 5-methoxy-7H-dibenzo[de,h]quinolin-7-one, 5-methoxy-6-hydroxy-7H-dibenzo[de,h]quinolin-7-one, 5-hydroxy-7H-dibenzo[de,h]quinolin-7-one and 5-methoxy-6H-dibenzo[de,h]quinolin-6-one were prepared either by oxidation of their 2,3-dihydro derivatives or by heating (2'-(3,4-dihydro-6,7-dimethoxyisoquinolin-1'-yl)phenyl)methylbenzoate with an acetic acid/sulfuric acid mixture at 100 degrees C. The structures were confirmed and 1H and 13C NMR spectra were completely assigned using two-dimensional NMR techniques.     

Antileukemic α-pyrone derivatives from the endophytic fungus Alternaria phragmospora

Four new (1–4) and two known (5 and 6) α-pyrone derivatives have been isolated from Alternaria phragmospora, an endophytic fungus from Vinca rosea, leaves. The isolated compounds were chemically identified to be 5-butyl-4-methoxy-6-methyl-2H-pyran-2-one (1), 5-butyl-6-(hydroxymethyl)-4-methoxy-2H-pyran-2-one (2), 5-(1-hydroxybutyl)-4-methoxy-6-methyl-2H-pyran-2-one (3), 4-methoxy-6-methyl-5-(3-oxobutyl)-2H-pyran-2-one (4), 5-(2-hydroxyethyl)-4-methoxy-6-methyl-2H-pyran-2-one (5), and 5-[(2E)-but-2-en-1-yl]-4-methoxy-6-methyl-2H-pyran-2-one (6). Compounds 2 and 4 showed moderate antileukemic activities against HL60 cells with IC₅₀ values of 2.2 and 0.9 μM and against K562 cells with IC₅₀ values of 4.5 and 1.5 μM, respectively.