Identification and biological activity of microbial metabolites of xanthohumol

Microbial transformation of xanthohumol using the culture broth of Cunninghamella echinulata NRRL 3655 afforded (2S)-8-[4"-hydroxy-3"-methyl-(2"-Z)-butenyl]-4',7-dihydroxy-5-methoxyflavanone (5) and (2S)-8-[5"-hydroxy-3"-methyl-(2"-E)-butenyl]-4',7-dihydroxy-5-methoxyflavanone (6). Xanthohumol (1) and flavanone 6 as well as (E)-2"-(2"'-hydroxyisopropyl)-dihydrofurano[2",3":4',3']-2',4-dihydroxy-6'-methoxychalcone (2), (2S)-2"-(2"'-hydroxyisopropyl)-dihydrofurano[2",3":7,8]-4'-hydroxy-5-methoxyflavanone (3) obtained with Pichia membranifaciens showed antimalarial activity against Plasmodium falciparum.     

Near-Infrared Hydrophobic Probes as Molecular Light Switch for CMC Determination of Triton X-100 Solution

The fluorescence behavior of two near-infrared (NIR) chromophores with linear alkyl chains of different lengths, 2-[4′chloro-7′(3″ethyl-2″benzothiaolinylidene)-3′,5′-(1″′3′″-propanediyl)-1′3′,5′-heptantriene-1′-yL]-3-ethylbenzothiazolium iodide (Probe Ⅰ) and 2-[4′chloro-7′(3″hexadecyl-2″benzothiazolinylidene)-3′,5′-(1′″,3′″-propanediyl)-1′,3′,5′-heptantriene-1′-yl]-3-ethylbenzothiazolium iodide (Probe Ⅱ), in aqueous solution containing different concentrations of surfactants was studied. The fluorescence of the probe with a short chain (probe Ⅰ) was completely quenched in water and aqueous solution containing a low concentration (below the critical micelle concentration,CMC) of surfactant Triton X-100. However, the fluorescence reappeared and reached maximum rapidly once the concentration of the surfactant approached the CMC. The probe with a long chain (probe II) displayed a similar fluorescence behavior but more dramatically fluorescent recovery in Triton X-100 system, which gave a direct in- dication for the micelle forming process and provided a simple method for the determination of the critical micelle concentration of the surfactant. The CMC values determined by this method were in good agreement with those obtained by other techniques. The fluorescence behavior of the two probes in other surfactant systems was also investigated.     

Structure Determination of the Products from the Acid-Catalyzed Condensation of Indole with Acetone

Four of the previously reported compounds obtained from the acid-catalyzed condensation of indole with acetone are now assigned the following structures: cis-4,4a,9,9a-tetrahydro-2-(1H-indol-3-yl)-4,4-dimethyl-3H-carbazole (2a), 1,1',4,4'-tetrahydro-1,1,1',1'-tetramethyl-3,3'(2H,2'H)-spirobi[cyclopent[b]indole] (4), 4,4a-dihydro-2-(3-1H-indolyl)-4,4-dimethyl-3H-carbazol-4a-ol (7), and 5-(2-aminophenyl)-1,3,4,5-tetrahydro-1,1,4,4-tetramethylcyclopent[kl]acridine (8). The structure of the novel rearrangement product 8 was solved by an X-ray crystal structure determination. The two previously reported autoxidation products of 4 are now assigned the following structures: 1,3',4,4'-tetrahydro-1,1,4',4'-tetramethyl-cis-dispiro[cyclopent[b]indole-3(2H),2'(5'H)-furan-5',3"-[3H]-indol]-2"(1"H)-one (5) and 1,4-dihydro-1,1,5',5'-tetramethylspiro[cyclopent[b]indole-3(2H),3'(4'H)-1-benzazocine]-2'(1'H),6'(5'H)-dione (6).     

4-(1-硫杂-2亚氨基-3,4-二氮杂-1,4-亚丁基)-4-脱氧阿维菌素B1a的合成

以阿维菌素B1a为原料经选择性C-5羟基保护、氧化合成5-O-烯丙氧羰基-5-氧代-5-脱氧阿维菌素B1a (3), 然后与N-取代氨基硫脲偶联, 缩合产物经MnO2氧化关环、脱保护得到10个未见文献报道的4-(1-硫杂-2-亚氨基- 3,4-二氮杂-1,4-亚丁基)-4-脱氧阿维菌素B1a (7a～7j). 目标化合物结构经1H NMR, 13C NMR和MS确证.     

Distance dependence of electron transfer in rigid,cofacially compressed,pi-stacked porphyrin-bridge-quinone systems

The electron-transfer (ET) dynamics of a series of unusually rigid pi-stacked porphyrin-quinone (P-Q) systems, in which sub-van der Waals interplanar distances separate juxtaposed porphyryl, aromatic bridge, and quinonyl components of these assemblies, are reported. The photoinduced charge separation (CS) and thermal charge recombination (CR) ET reactions of [5-[8'-(2',5'-benzoquinonyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (1a-Zn), [5-[8'-(4'-[8'"-(2'"',5'"'-benzoquinonyl)-1'"-naphthyl]-1'-phenyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (2a-Zn), and [5-(8'-[4'-(8'"-[4'"'-(8'"-[2'"',5'"'-benzoquinonyl]-1'"-naphthyl)-1'"'-phenyl]-1'"-naphthyl)-1'-phenyl]-1'-naphthyl)-10,20-diphenylporphinato]zinc(II) (3a-Zn) in CH(2)Cl(2) were investigated by pump-probe transient absorption spectroscopy. Analyses of these data show that the phenomenological ET distance dependence (beta) for both the CS and CR reactions in these systems is soft (beta(CS) = 0.43 A(-1); beta(CR) = 0.35 +/- 0.16 A(-1)). This work demonstrates that simple aromatic building blocks such as benzene, which are characterized by highly stabilized filled molecular orbitals and large HOMO-LUMO gaps, can provide substantial D-A electronic coupling when organized within a pi-stacked structural motif that features a modest degree of arene-arene interplanar compression.     

The C-disaccharide alpha-C(1-->3)-mannopyranoside of N-acetylgalactosamine is an inhibitor of glycohydrolases and of human alpha-1,3-fucosyltransferase VI. Its epimer alpha-(1-->3)-mannopyranoside of N-acetyltalosamine is not

The radical C-glycosidation of (-)-(1S,4R,5R, 6R)-6-endo-chloro-3-methylidene-5-exo-(phenylseleno)-7-ox abi cyclo[2. 2.1]heptan-2-one ((-)-4) with 2,3,4, 6-tetra-O-acetyl-alpha-D-mannopyranosyl bromide gave (+)-(1S,3R,4R, 5R,6R)-6-endo-chloro-5-exo-(phenylseleno)-3-endo-(1',3',4', 5'-tetra-O-acetyl-2', 6'-anhydro-7'-deoxy-D-glycero-D-manno-heptitol-7'-C-yl)-7-oxabi cyc lo[ 2.2.1]hept-2-one ((+)-5) that was converted into (+)-(1R,2S,5R, 6R)-5-acetamido-3-chloro-2-hydroxy-6-(1',3',4',5'-tetra-O-acetyl)-2', 6'-anhydro-7'-deoxy-D-glycero-D-manno-heptitol-7'-C-yl)cyclohex -3-en- 1-yl acetate ((+)-10) and into (+)-(1R,2S,5R, 6S)-5-bromo-3-chloro-2-hydroxy-6-(1',3',4',5'-tetra-O-acetyl-2', 6'-anhydro-7'-deoxy-D-glycero-D-manno-heptitol-7'-C-yl)cyclohex -3-en- 1-yl acetate ((+)-19). Ozonolysis of (+)-10 and further transformations provided 2-acetamido-2,3-dideoxy-3-C-(2', 6'-anhydro-7'-deoxy-D-glycero-D-manno-heptitol-7'-C-yl)-D-galac tos e (alpha-C(1-->3)-D-mannopyranoside of N-acetylgalactosamine (alpha-D-Manp-(1-->3)CH(2)-D-GalNAc): 1). Displacement of the bromide (+)-19 with NaN(3) in DMF provided the corresponding azide ((-)-20) following a S(N)2 mechanism. Ozonolysis of (-)-20 and further transformations led to 2-acetamido-2,3-dideoxy-3-C-(2', 6'-anhydro-7'-deoxy-D-glycero-D-manno-heptitol-7'-C-yl)-D-talose (alpha-C(1-->3)-D-mannopyranoside of N-acetyl D-talosamine (alpha-D-Manp-(1-->3)CH(2)-D-TalNAc): 2). The neutral C-disaccharide 1 inhibits several glycosidases (e.g., beta-galactosidase from jack bean with K(i) = 7.5 microM, alpha-L-fucosidase from human placenta with K(i) = 28 microM, beta-glucosidase from Caldocellum saccharolyticum with K(i) = 18 microM) and human alpha-1, 3-fucosyltransferase VI (Fuc-TVI) with K(i) = 120 microM whereas it 2-epimer 2 does not. Double reciprocal analysis showed that the inhibition of Fuc-TVI by 1 displays a mixed pattern with respect to both the donor sugar GDP-fucose and the acceptor LacNAc with K(i) of 123 and 128 microM, respectively.     

酰氨基硫脲及相关杂环衍生物的研究XXIX: 2-(3'-溴苯胺基)-5-[5'-氨基-1'-(4"-氯苯基)-1',2',3'-三唑-4'-基]-1,3,4-噻二唑的晶体结构

经1-[5'-氨基-1'-(4"-氯苯基)-1',2',3'-三唑-4'-甲酰基]-4-(3'-溴苯基)-3-氨基硫脲在浓硫酸作用下制得2-(3'-溴苯胺基)-5-[5'-氨基-1'-(4"-氯苯基)-1',2',3'-三唑-4'-基]-1,3,4-噻二唑化合物。该化合物的晶体结构经X射线衍射分析确定, 化合物属三斜晶系, P1空间群, a=1.1784(2), b=1.4455(2),c=1.1353(1)nm; α=100.68(1), β=109.50(1), γ=79.89(1)°; V=1.7779nm^3; 分子式C~1~6H~1~1BrClN~7S, Mr=448.75; Dc=1.673g/cm^3, Z=4,μ=58.16cm^-^1, 最终偏离因子R=0.084, Rw=0.086。分析化合物的键长, 键角数据表明, 该分子具有离域π键结构。     

Site specificity of metal ions in heterodinuclear complexes derived from an "end-off" compartmental ligand

A phenol-based "end-off" compartmental ligand, 2-[N-[2-(dimethylamino)ethyl]iminomethyl]-6-[N,N-di(2-pyridylmethyl)aminomethyl]-4-methylphenol (HL), having a bidentate arm and a tridentate arm attached to the 2 and 6 positions of the phenolic ring, has afforded the following heterodinuclear M(a)(II)M(b)(II) complexes: [CuM(L)(AcO)(2)]ClO(4) (M = Mn (1), Fe (2), Co (3), Ni (4), Zn (5)), [ZnM(L)(AcO)(2)]ClO(4) (M = Co (6), Ni (7)), and [CuNi(L)(AcO)(NCS)(2)] (8). 1.MeOH (1'), 2.MeOH (2'), 3.MeOH (3'), 4.MeOH (4'), 5.MeOH (5'), and 7.MeOH (7') are isostructural and have a heterodinuclear core bridged by the phenolic oxygen atom of L(-) and two acetate groups. In 1'-5' the Cu(II) is bound to the bidentate arm and has a square-pyramidal geometry with one acetate oxygen at the apical site. The M(II) is bound to the tridentate arm and has a six-coordinate geometry together with two acetate oxygen atoms. In the case of 7' the Zn is bound to the bidentate arm and the Ni is bound to the tridentate arm. 8.2-PrOH (8') has a dinuclear core bridged by the phenolic oxygen atom of L(-) and one acetate group. The Cu bound to the bidentate arm has a square-pyramidal geometry with an isothiocyanate group at the apical site. The Ni bound to the tridentate arm has a six-coordinate geometry with further coordination of an isothiocyanate group. The site specificity of the metal ions is discussed together with the crystal structure of [Cu(4)(L)(2)(AcO)(3)](ClO(4))(3).H(2)O (9) prepared in this work.     

New condensed indoline bis-spiropyrans

The synthesis of new condensed indoline bis-spiropyrans from isomeric hexamethyldihydroindolo-[4,5-e]-and -[7,6-g]indoles, and also from hexamethyldihydrobenzo[e]pyrrolo[3,2-g]indole in three stages has been generalized. By condensation of the isomeric bis-analogs of Fischer's bases obtained at the second stage with salicylic aldehydes, the following bis-spiro compounds have been synthesized: 6,6"-dinitro-, 6,6",8,8"-tetranitro-, 6,6",8,8"-tetrabromo-1',3',3',6',8',8'-hexamethyldispiro[chromene-2,2'-indolino[7,6-g]indoline-7',2"-chromenes], 6,6"-dinitro-, 6,6",8,8"-tetranitro-, 6,6",8,8"-tetrabromo-1',1',3',8',10',10'-hexamethyldispiro[chromene-2,2'-indolino[4,5-e]indoline-9',2"-chromenes], 6,6"-di-nitro-, 6,6"-dibromo-, and 6,6",8,8"-tetrabromo-1',1',8,8'-tetramethyl-1',4',5',8'-tetrahydrodispiro-[chromene-2,2'-dipyrrolo[1,2,3-d,e:3,2,1-i,j]benzo[g]quinoxaline-7',2"-chromenes].     

2-芳胺基-5-[5’-氨基-1’-(4”-氯苯基)-1’,2’,3’-三唑-4’-基]——1,3,4-噁二唑的合成

利用1-[5’-氨基-1’-(4”-氯苯基)-1’,2’,3’-三唑-4’-甲酰基]-4-芳基氨基硫脲在汞盐Hg(OAc)_2-HOAc中加热缩合,制得11种新的2-芳胺基-5-[5’-氨基-1’-(4”-氯苯基)-1’,2’,3’-三唑-4’-基]-1,3,4-噁二唑。所有化合物的结构经元素分析,IR、MS以及~1HNMR确认。选择代表物作生测试验,结果表明,2b,2k在MIC3.1mg/L时,对大肠杆菌及金黄色葡萄球菌繁殖有明显抑制。     

"Dimers" and "trimers" of tetrahydroindenes and hexahydroazulenes, respectively generated from [2-(1-cycloalkenyl)ethynyl]carbene complexes (M = W, Cr) by cascade cyclization/cycloaddition reactions

A cascade of cyclization/cycloaddition reactions was triggered by addition of protic oxygen nucleophiles ROH 2 (RO = CH3CO2, PhCO2, PhO) to [2-(1-cyclohexenyl)ethynyl]carbene complexes 1b and 1c (M=W, Cr, respectively), affording highly strained "dimers" 11/11' and "trimers" 12 of the carbene ligand. The first reaction step involved the formation of 1-metalla1,3,5-hexatrienes 7, which readily gave tetrahydroindenes 8 by pi cyclization and extrusion of the metal unit. "Dimers" 11/11' were generated from tetrahydroindenes 8 by a highly exo selective [4+2] cycloaddition of compounds 1b and 1c to afford 1-metalla-1,3,5-hexatriene intermediates 9, and a spontaneous pi cyclization of the latter compounds involving the disengagement of the metal unit. Propenylidene cyclohexenes 13/13' were formed in "ene"-type side reactions to the pi cyclization of 1-metalla-1,3,5-hexatrienes 7, by loss of the metal unit. "Dimers" 11 were transformed into "trimers" 12 by a [4+2] cycloaddition and subsequent pi-cyclization of the resulting 1-metalla-1,3,5-hexatriene system. The course of the reaction was elucidated by means of model reactions with (2-phenylethynyl)carbene complex 14, in which 1-metalla-1,3,5-hexatriene intermediates 16 and 17 were isolated and characterized. Alkynyl benzene derivatives 19 were obtained by an unprecedented ring-expansion of a cyclopentadiene unit of "dimers" 11a and 11c, involving the insertion of a carbene carbon atom of compound 14 into a C=C bond. A reaction cascade leading to "dimers" 24/24' could also be triggered by treatment of compounds 2 with [2-(1-cycloheptenyl)ethynyl]carbene tungsten complex 1d.     

2-芳胺基-5-[5′-氨基-1′-(4″-氯苯基)-1′,2′,3′-三唑-4′-基]-1,3,4-噻二唑的合成~≠

1-[5’-氨基-1’-(4”-氯苯基)-1,2,3-三唑-4’-甲酰基]-4-芳基-3-氨基硫脲在浓硫酸催化下环化得到2-芳胺基-5-[5’-氨基-1’-(4”-氯苯基)-1’,2’,3’,-三唑-4’-基]-1,3,4-噻二唑2a～i,依次法合成了九个标题化合物,收率为30～74％。化合物2i的结构用X-光衍射单晶分析确证。     

Synthesis of Novel Flavanone Derivatives and Their Anti Staphylococcus aureus Evaluation

The authors synthesized two novel flavanones bearing iso-pentenyl side chain and evaluated their anti Staphylococcus aureus(S. aureus) activity. The target compounds 7a[2-5'-(1",2"-dimethylallyl)-2'-methoxy-4',5,7-tetrahydroxyflavanone] and 7b[2-5'-(1",2"-dimethylallyl)-3'-methoxy-4',5,7-tetrahydroxyflavanone] were synthesized respectively through total four steps starting from 2,4,6-trihydroxy acetophenone(3) and the corresponding iso-pentenyl substituted benzaldehyde(1), in which the 1,2-dimethyl-2-propenyl group had been introduced previously via abnormal Claisen rearrangement. The bioactivities of the two flavanones against S. aureus strains ATCC 25923, 29213, and MRSA 252 were evaluated, showing the same minimum inhibitory concentration(MIC) value of 16 μg/mL.     

Photoinduced reactions of 1-acetylisatin with phenylacetylenes

[reaction: see text]Photoinduced reactions of 1-acetylisatin 1 with diphenylacetylenes 2a-2c afforded the corresponding 3-methylene-2-indolones 4a-4e and 5a-5e in 80-90% yields via a spirooxetene intermediate. Similar irradiation of 1 with phenylacetylene, on the other hand, resulted in efficient formation of two diastereoisomeric dispiro[3H-indole-3,2'-furan-3',3"-(3H)-indole]-2,5',2"(2H,5'H,2"H )triones 6 and 7 via a reaction sequence with initial formation of the spirooxetene intermediate. The regioselectivity in the photocycloaddition of 1 with phenylacetylene and the reaction mechanism for the formation of 6 and 7 are discussed.     

Biotransformation of pinoresinol diglucoside to mammalian lignans by human intestinal microflora,and isolation of Enterococcus faecalis strain PDG-1 responsible for the transformation of (+)-pinoresinol to (+)-lariciresinol

By anaerobic incubation of pinoresinol diglucoside (1) from the bark of Eucommia ulmoides with a fecal suspension of humans, eleven metabolites were formed, and their structures were identified as (+)-pinoresinol (2), (+)-lariciresinol (3), 3'-demethyl-(+)-lariciresinol (4), (-)-secoisolariciresinol (5), (-)-3-(3", 4"-dihydroxybenzyl)-2-(4'-hydroxy-3'-methoxybenzyl)butane-1, 4-diol (6), 2-(3', 4'-dihydroxybenzyl)-3-(3", 4"-dihydroxybenzyl)butane-1, 4-diol (7), 3-(3"-hydroxybenzyl)-2-(4'-hydroxy-3'-methoxybenzyl)butane-1, 4-diol (8), 2-(3', 4'-dihydroxybenzyl)-3-(3"-hydroxybenzyl)butane-1, 4-diol (9), (-)-enterodiol (10), (-)-(2R, 3R)-3-(3", 4"-dihydroxybenzyl)-2-(4'-hydroxy-3'-methoxybenzyl)butyrolactone (11), (-)-(2R, 3R)-2-(3', 4'-dihydroxybenzyl)-3-(3", 4"-dihydroxybenzyl)butyrolactone (12), (-)-(2R, 3R)-3-(3"-hydroxybenzyl)-2-(4'-hydroxy-3'-methoxybenzyl)butyrolactone (13), 2-(3', 4'-dihydroxybenzyl)-3-(3"-hydroxybenzyl)butyrolactone (14), 2-(3'-hydroxybenzyl)-3-(3", 4"-dihydroxybenzyl)butyrolactone (15) and (-)-(2R, 3R)-enterolactone (16) by various spectroscopic means, including two dimensional (2D)-NMR, mass spectrometry and circular dichroism. A possible metabolic pathway was proposed on the basis of their structures and time course experiments monitored by thin-layer chromatography. Furthermore, a bacterial strain responsible for the transformation of (+)-pinoresinol to (+)-lariciresinol was isolated from a human fecal suspension and identified as Enterococcus faecalis strain PDG-1.     

2-芳胺基-5-[5'-氨基-1'-(4"-氯苯基)-1',2',3'-三唑-4'-基]-1,3,4-噻二唑的合成

1-[5'-氨基-1'-(4"-氯苯基)-1,2,3-三唑-4'-甲酰基]-4-芳基-3-氨基硫脲在浓硫酸催化下环化得到2-芳胺基-5-[5'-氨基-1'-(4"-氯苯基)-1',2',3',-三唑-4'-基]-1,3,4-噻二唑2a-i, 依此法合成了九个标题化合物, 收率为30-74%。化合物2i的结构用X-光衍射单晶分析确证。     

Chemical constituents of Melicope ptelefolia

Phytochemical investigations on the methanolic extract of Melicope ptelefolia Champ ex Benth. resulted in the isolation of three new compounds, identified as 3beta-stigmast-5-en-3-ol butyl tridecanedioate (melicoester) (1), (2Z, 6Z, 10Z, 14Z, 18Z, 22Z, 26E)-3', 7', 11', 15', 19', 23', 27', 31'-octamethyldotriaconta-2, 6, 10, 14, 18, 22, 26, 30-octadecanoate (melicopeprenoate) (2) and p-O-geranyl-7"-acetoxy coumaric acid (3). The compounds were isolated along with twenty-one other known compounds, lupeol (4), oleanolic acid (5), kokusaginine (6) genistein (7), p-O-geranyl coumaric acid (8), 4-stigmasten-3-one (9), 3beta-hydroxystigma-5-en-7-one (10) cis-phytyl palmitate (11), dodecane, dodecan-1-ol, ceryl alcohol, hentriacontanoic acid, eicosane, n-amyl alcohol, caprylic alcohol, octatriacontane, nonatriacontane, hexatriencontan-1-ol, methyl octacosanoate, beta-sitosterol, beta-sitosterol glucoside. Structures of all the compounds were established on the basis of MS and 1D and 2D NMR spectral data, as well as comparison with reported data.     

Isolation of Six New Flavonoids from Melicope triphylla

Six new flavonoids-5-hydroxy-3,8-dimethoxy-3',4':6,7-bismethylenedioxyflavone (1), 3,3',4',5-tetramethoxy-7-(3-methylbut-2-enyloxy)flavone (2), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,3',4',5-tetramethoxyflavone (3), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,5-dimethoxy-3',4'-methylenedioxyflavone (4), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,3',4',5,8-pentamethoxyflavone (5), and 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,5,8-trimethoxy-3',4'-methylenedioxyflavone (6)-were isolated from the leaves of Melicope triphylla. In addition, six already known flavonoids were also detected: 5-hydroxy-3,6,7-trimethoxy-3',4'-methylenedioxyflavone (7), 5,7-dihydroxy-3,3',4',8-tetramethoxyflavone (8), 4',5-dihydroxy-3,3',7,8-tetramethoxyflavone (9), 3,5,6,7,8-pentamethoxy-3',4'-methylenedioxyflavone (10), 3,5,6,7-tetramethoxy-3',4'-methylenedioxyflavone (11), and 3,3',4',5,6,7,8-heptamethoxyflavone (12). The structures of the new compounds were established by spectroscopic methods. Compound 2 displayed ichthyotoxic activity against Japanese killifish (medaka in Japanese) (Oryzias latipes var.) at 10?ppm.     

Polyhydroxyoligothiophenes. 2. Hydrogen-Bonding-Oriented Solid State Conformation of 3,3'-Bis(2-hydroxyethyl)-2,2'-bithiophene and Regioselective Synthesis of the Corresponding Head-to-Head/Tail-to-Tail Quater- and Sexithiophene

This paper reports the X-ray structure of 3,3'-bis(2-hydroxyethyl)-2,2'-bithiophene (1), which is the building block for the synthesis of head-to-head/tail-to-tail 2-hydroxyethyl-substituted oligothiophenes. Contrary to all the bithiophenes reported so far, 1 exhibits a noncoplanar anti conformation and an inter-ring twist angle (67.5 degrees ) which is the largest ever measured for adjacent rings of alpha-conjugated oligothiophenes. This unusual conformation appears to be dictated by intermolecular hydrogen-bonding interactions involving the OH groups, which bind the molecule in close packed layers. The paper also describes the regioselective synthesis of the dimer and the trimer of 1, namely of 3,3',4",3"'-tetrakis(2-hydroxyethyl)-2,2':5',2":5",2"'-quaterthiophene (3c) and of 3,3',4",3"',4",3"'-hexakis(2-hydroxyethyl)-2,2':5',2":5",2"':5"',2":5",2"'-sexithiophene (4b). 3c And 4b were obtained through palladium(0)-catalyzed coupling of the mono- and distannanes of the tetrahydropyranyl derivative of 1 with the appropriate monobromo compound (Stille's reaction). Finally, the paper reports force-field calculations which suggest that the low lambda(max) values measured for 1, 3c, and 4b are also the result of intramolecular hydrogen-bonding interactions which favor highly twisted conformations in solution.     

二醇及氨基醇类鬼臼毒素衍生物的合成

以天然产物鬼臼毒素(1)为原料，合成了四种二醇及氨基醇类鬼臼毒素衍生物：4-O-乙基表鬼臼苦醇(4)，(1R,2S,3R,4S)-1-3',4',5'-三甲氧基苯基-2-氨甲基-3-羟甲基-4-乙氧基-6,7-亚甲二氧基-1,2,3,4-四氢萘(5)，(1R,2S,3R,4S)-1-3',4',5'-三甲氧基苯基-3-羟甲基-2-氨基-4-乙氧基-6,7-亚甲二氧基-1,2,3,4-四氢萘(6)和4-O-异丙基表鬼臼苦醇(7)。4～7及中间产物8～11都是新化合物。