Total synthesis of (+)-hatomarubigin B.

The first total synthesis of (+)-hatomarubigin 3 is described. The tetra-O-acetyl diborate promoted Diels-Alder reaction of 5-hydroxy-8-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosyloxy)-1,4-naphthoquinone 8 and (E, 1R*,5R*)-3-(2'-methoxyvinyl)cyclohex-2-enol (+/-)-7 gave a mixture of four cycloadducts from which (1S,3S,6S,6aR,12aR,12bS)-1,8-dihydroxy-6-dimethoxy-1-hydroxy-3-methyl-11-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosyloxy)-1,2,3,4,6,6a,12a,12b-octahydrobenz[a]anthracene-7,12-dione 12 was isolated in 51% yield. Selective methylation and acetylation of 12 gave (1S,3S,6S,6aR,12aR,12bS)-1-acetoxy-6,8-dimethoxy-3-methyl-11-(2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyloxy)-1,2,3,4,6,6a,12a,12b-octahydrobenz[a]anthracene-7,12-dione 10a. Sequential aromatization, photooxidation and hydrolysis of the glucosyl unit gave (+)-3 (98% ee) in an 8% overall yield from 8.     

Polymethylated DOTA ligands. 1. Synthesis of rigidified ligands and studies on the effects of alkyl substitution on acid-base properties and conformational mobility

This work describes the synthesis and the conformational properties of new polymethylated macrocyclic ligands of potential interest for magnetic resonance imaging. M4cyclen, (2S,5S,8S,11S)-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecane, was obtained by cyclotetramerization of (2S)-1-benzyl-2-methylaziridine followed by catalytic hydrogenation. The ligands M4DOTA, [(2S,5S,8S,11S)-4,7,10-tris-carboxymethyl-2,5,8,11-tetramethyl- 1,4,7,10-tetraazacyclododecan-1-yl]acetic acid, and M4DOTMA, (R)-2-[(2S,5S,8S,11S)-4,7,10-tris-((R)-1-carboxyethyl)-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecan-1-yl]propionic acid, were prepared by carboxyalkylation of M4cyclen in the presence of Na(2)CO(3). The triacetic ligand M4DO3A, [(2S,5S,8S,11S)-4,7-bis-carboxymethyl-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecan-1-yl]acetic acid, was obtained in good yields without traces of M4DOTA if NaHCO(3) was the acid scavenger when adding the carboxylic arms. In the same conditions, cyclen yielded M4DOTA in 82% yield. The difference between the reactivity of cyclen and M4cyclen is assigned to the high basicity of the substituted tetraamine as estimated by NMR titration. The one- and two-dimensional (1)H and (13)C NMR spectra of M4DOTA and M4DOTMA in the H(4)L or H(6)L(2+) forms are interpreted as arising from a slow exchange between two elongated geometries in which the methyl substituents are in one of the two possible equatorial-like positions, either close to or away from the carboxylic arms. The axial-like positions are sterically too crowded and cannot be occupied by the methyl groups. An elongated conformation is also adopted by DOTMA, (R)-2-[4,7,10-tris-((R)-carboxyethyl)-1,4,7,10-tetraazacyclododecan-1-yl]propionic acid, in the H(6)L(2+) form. The rigidification of the polymethylated ligands allows a detailed NMR analysis that cannot be carried out on the parent unsubstituted ligand DOTA.     

Characterization of a new decahydropyridoquinoline from Indigofera longeracemosa Boiv. ex Baill. (Fabaceae)

Repeated silica gel chromatography of the dichloromethane extract of air-dried stems of Indigofera longeracemosa followed by reverse-phase HPLC separation yielded a new decahydropyridoquinoline, rel-(3S, 5R, 6S, SR, 8aR, 12aR)-8-acetoxy-6-butyl-3-isothiocyanatodecahydropyrido (2,1) quinoline.     

Megastigmane glucosides from Equisetum debile and E. diffusum

A new megastigmane diglucoside, (3S,5R,6S,7E,9S)-megastigman-7-ene-5,6-epoxy-3,9-diol 3,9-O-beta-D-diglucopyranoside (3), was isolated from the aerial portion of Equisetum debile along with macarangioside D (debiloside A), sammangaoside A, (6R,9S)-3-oxo-alpha-ionol 9-O-beta-D-glucopyranoside, debiloside B, kaempferol 3-O-sophoroside, kaempferol 3,7-O-beta-D-diglucopyranoside, kaempferol 3-O-sophoroside-7-O-beta-D-glucopyranoside, phenylethyl O-beta-D-glucopyranoside, (Z)-3-hexenyl O-beta-D-glucopyranoside, (7S,8R)-dehydrodiconiferyl 4-O-beta-D-glucopyranoside, and L-tryptophan. The absolute configuration at C-6 of the original structure of debilo-side A was revised to 6R-configuration, and was identical with macarangioside D (1). From the aerial portion of E. diffusum, four compounds, sammangaoside A, kaempferol 3-O-sophoroside and L-tryptophan and (3S,5R,6S,7E,9S)-megastigman-7-ene-5,6-epoxy-3,9-diol 3-O-beta-D-glucopyranoside were identified. The spectroscopic data of (3S,5R,6S,7E,9S)-megastigman-7-ene-5,6-epoxy-3,9-diol 3-O-beta-D-glucopyranoside (13) were found to be identical with corchoionoside A (9R-isomeric compound). The structure of corchoionoside A was also discussed. Structure determinations were based on physical data and spectroscopic evidence.     

Two new ceramides from the stems of Piper betle L.

<正>Two new ceramides,(2S,3S,4R)-2-N-[(2'R)-2'-hydroxypentacosanoylamino]-nonacosane-1,3,4-triol(1) and(2S,3S,4R,8E)-2- N-[(2'R)-2'-hydroxytetracosanoylamino]-8-eicosylene-1,3,4-triol(2) have been isolated from the stems of Piper betle L.collected from Baoshan city of Yunnan Province in China.Their structures were determined by spectroscopic and chemical methods.     

Two new terpenoids from endophytic fungus Periconia sp. F-31

Two new terpenoids, (+)-(3S,6S,7R,8S)-periconone A (1) and (-)-(1R,4R,6S,7S)-2-caren-4,8-olide (2), have been isolated from an endophytic fungus Periconia sp., which was collected from the plant Annona muricata. Their structures were elucidated on the basis of extensive spectroscopic analyses. In the in vitro assays, the two compounds showed low cytotoxic activities against six human tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, A2780 and MCF-7) with IC(50)>10(-5) M.     

Heme-Peptide Models for Hemoproteins. 1. Solution Chemistry of N-Acetylmicroperoxidase-8

An improved method for the preparation of the heme octapeptide acetyl-MP8, obtained by proteolysis of horse heart cytochrome c, is described. AcMP8 obeys Beer's law at pH 7.0 in aqueous solution up to a concentration of 3 x 10(-)(5) M. The self-association constant measured at 25 degrees C (log K(D) = 4.04) is an order of magnitude lower than that for MP8, reflecting the role of the N-acetyl protecting group in abolishing intermolecular coordination. However, AcMP8 does form pi-stacked dimers in aqueous solution with increasing ionic strength. A more weakly packed pi-pi dimer reaches a maximum abundance at approximately 3 M ionic strength, but a more tightly packed dimer is favored at &mgr; > 3 M. An equilibrium model based on charge neutralization by specific binding of Na(+) ions gives a total molecular charge of 3- for AcMP8 at pH 7.0 and a self-association constant log K(D) = 4.20. AcMP8 exhibits six spectroscopically active pH-dependent transitions. The Glu-21 c-terminal carboxylate binds to the heme iron at low pH (pK(a) = 2.1) but is substituted by His-18 (pK(a) = 3.12) as the pH increases. The two heme propanoic acid substituents ionize with pK(a)'s of 4.95 and 6.1. This is followed by ionization of iron-bound water with a pK(a) = 9.59, DeltaH = 48 +/- 1 kJ mol(-)(1), and DeltaS = -22 +/- 3 J K(-)(1) mol(-)(1). The electronic spectra indicate that AcMP8 is predominantly in the S = (5)/(2) state at pH 7.0, while the hydroxo complex at pH 10.5 corresponds to an equilibrium mixture of S = (5)/(2) and S = (1)/(2) states at 25 degrees C. In the final transition, His-18 ionizes to form the S = (1)/(2) histidinate complex with a pK(a) of 12.71. AcMP8 is relatively stable under alkaline conditions, dimerizing slowly at high pH (k = 2.59 +/- 0.14 M(-)(1) s(-)(1)) to form a high-spin &mgr;-oxo-bridged species. The pH-dependent behavior of AcMP8 in the presence of excess 3-cyanopyridine, however, is markedly different. At low pH, AcMP8 simultaneously binds the exogenous ligand and the Glu-21 c-terminal carboxylate with a pK(a) < 2. His-18 replaces the carboxylate ligand at higher pH (pK(a) = 2.60), and both heme propanoic acid groups ionize with a mean pK(a) = 5.10. Unlike AcMP8.OH(-), the axial histidine of the 3-CNPy complex ionizes at near neutral pH (pK(a) = 7.83), prior to being replaced by OH(-) (pK(a) = 10.13). The sixth transition in the AcMP8/3-CNPy system produces the bis(hydroxo) complex (pK(a) > 13).     

Synthesis of new [8Fe-7S] clusters: a topological link between the core structures of P-cluster, FeMo-co, and FeFe-co of nitrogenases

A coordinatively unsaturated dinuclear iron(II) complex of bulky thiolates, [(TipS)Fe(micro-SDmp)]2 (1; Tip = 2,4,6-(i)Pr(3)C(6)H(2), Dmp = 2,6-(mesityl)(2)C(6)H(3)), was synthesized from stepwise reactions of Fe{N(SiMe(3))2}2 with 1 equiv of HSDmp and then with 1 equiv of HSTip. Complex 1 was found to react with elemental sulfur (S8) in toluene to generate a new class of [8Fe-7S] cluster, [(DmpS)Fe(4)S(3)]2(micro-SDmp)2(micro-STip)(micro(6)-S) (2). The cluster 2 was also produced from one-pot reactions of Fe{N(SiMe(3))2}2 + HSDmp + HSTip + S8 (8:6:10:7/8) and Fe3{N(SiMe(3))2}2(micro-STip)4 + HSDmp + S8 (8/3:16/3:7/8), where another [8Fe-7S] cluster, [(TipS)Fe(4)S(3)]2(micro-SDmp)2{micro-N(SiMe(3))2}(micro(6)-S) (3), was also found as a minor byproduct. In either of the clusters, two Fe(4)S(3) incomplete cubane units are connected by three anionic ligands, namely three thiolate S atoms for 2 or two thiolate S atoms and one amide N atom for 3, and one hexa-coordinate S atom resides at the center of the [8Fe-7S] core. They have a common Fe(II)(5)Fe(III)3 oxidation states, and an S = 1/2 ground spin state was indicated by rhombic EPR signals at 10 K with g = 2.19, 2.07, and 1.96 for 2 and g = 2.13, 2.06, and 1.93 for 3. The structural relevance of clusters 2 and 3 to P-cluster, FeMo-co, and FeFe-co of nitrogenases is discussed.     

钴原子簇化合物研究Ⅴ.含硫脲桥基三钴硫羰基簇合物的合成和结构

本文通过Co~2(CO)~8与5个取代硫脲R^1NHC(S)NHR^2反应,制得了通式Co~3(CO)~7(μ~3-S)[μ-η^2-R^1NC(S)NHR^2]5个新簇合物.除用碳氢氮元素分析、IR、^1HNMR和MS表征它们的结构外,还用X光衍射法测得R^11=Ph,R^2=CH~2Ph簇合物的单晶结构.该簇合物属三斜晶系,PI空间群.晶胞参数如下:a=0.9116(1),b=1.2289(2),c=1.2518(2)nm,a=115.56(1),β=100.92(2),γ93.29(1)°;z=2,Ⅴ=1226.2×10^-5nm^3;D~c=1.75g.cm^-3;μ=22.099cm^-1,F(000)=646.结构分析表明,该分子中的Co^3S原子构成三角锥分子骨架,所有CO为钴原子的端羰配体,而PhNC(S)NHCH~2Ph以S原子和与苯基相连的N原子分别与两个钴原子配位,形成Co~2NCS五圆环结构.     

(Trifluoromethyl)sulfanyl sulfinylimine, CF3SNSO. Structure and conformation in the electronic ground and excited states

The molecular structure of (trifluoromethyl)sulfanyl sulfinylimine, CF₃---S---N=S=O, was determined by gas electron diffraction (GED) and ab initio calculations (HF/3–21G*, HF/6–31+G* and MP2/6–31+G*). Experimental and theoretical methods result in a structure with planar C---S---N=S=O skeleton (C_s symmetry), anti orientation of the S---C bond relative to the N=S bond and syn orientation of the S---N bond relative to the S=O double bond (anti-syn structure). The following skeletal parameters (r_a values with 3σ uncertainties) were derived in the GED analysis: S---C, 1.831(4) Å; S---N, 1.684(5) Å; N=S, 1.538(6) Å; S=O, 1.453(6) Å; C---S---N, 94.6(8)°; S---N=S, 120.6(6)°; N=S=O: 116.5(8)°. A normal coordinate analysis based on FTIR (gas), FTIR (matrix) and Raman (liquid) spectra was performed. The UV (gas) spectrum was recorded and interpretation of the resonance Raman effect leads to the conclusion that the molecular symmetry (C_s) is retained upon electronic excitation.     

Studies on the constituents of Broussonetia species X. Six new alkaloids from Broussonetia kazinoki Sieb.

Six new alkaloids, broussonetines W, X, M1, U1, J3, and J2 (1-6) were isolated from the branches of Broussonetia kazinoki SIEB. (Moraceae) as minor constituents. They were formulated as (2R,3R,4R,5R)-2-hydroxy-methyl-3,4-dihydroxy-5-17-(cyclohexy-2-on-1(6)-enyl)heptyllpyrrolidine (1), (2R,3S,4R,5R)-2-hydroxymethyl-3,4-dihydroxy-5-17-(cyclohexy-2-on-1(6)-enyl)heptyl]pyrrolidine-4-O-beta-D-glucopyranoside (2), (2R,3R,4R,5R)-2-hydroxymethyl-3,4-dihydroxy-5-[(9R)-9,13-dihydroxytridecyl]- pyrrolidine (3), (2S,3S,4S)-2-hydroxymethyl-3,4-dihydroxy-5-(10-oxo-13-hydroxytridecyl)-5- pyrroline (4), (2R)-2-[(IS,2S)-1,2-dihydroxy-8-1(2R,3R,4R,5R)-5-(2-hydroxymethyl-3,4-dihydroxy-1-acetylpyrrolidinyl)loctyl]piperidine (5), (2R)-2-[(1S,2S)-1,2-dihydroxy-8-[(2R,3R, 4R,5R)-5-(2-hydroxymethy]-3,4-dihydroxypyrrolidinyl)]octyl]piperidine (6).     

Preparative separation of 1,3,6-pyrenetrisulfonic acid trisodium salt from the color additive D&C Green No. 8 (pyranine) by pH-zone-refining counter-current chromatography

In developing analytical methods for batch certification of the color additive D&C Green No. 8 (G8), the U.S. Food and Drug Administration needed the trisodium salt of 1,3,6-pyrenetrisulfonic acid (P3S) for use as a reference material. Since P3S was not commercially available, preparative quantities of it were separated from portions of a sample of G8 that contained ～3.5% P3S. The separations were performed by pH-zone-refining counter-current chromatography using dodecylamine (DA) as the hydrophobic counterion. The added DA enabled partitioning of the polysulfonated components into the organic stationary phase of the two-phase solvent system used, 1-butanol-water (1:1). Thus, a typical separation that involved 20.3g of G8, using sulfuric acid as the retainer acid and 20% DA in the stationary phase and 0.1M sodium hydroxide as the mobile phase, resulted in ～0.58 g of P3S of greater than 99% purity. The identification and characterization of the separated P3S were performed by elemental analyses, proton nuclear magnetic resonance, high-resolution mass spectrometry, ultra-violet spectra, and high-performance liquid chromatography.     

Enantiospecific synthesis of polyhydroxylated indolizidines related to castanospermine:1 1-deoxy-castanospermine.

Enantiospecific synthesis of (6S,7R,8R,8aR)-6,7,8- trihydroxyindolizidine ( 1-deoxy-castanospermine ) (3) is described from readily available D-glucose, where the key step involves oxidative bromination of a benzylidene acetal to afford 8-azido-3-o-benzoyl-5-bromo-5,6,7,8-tetradeoxy-1,2-o-isopropylidene-β-L-ido-octose (16). The synthetic indolizidine (3) was tested against a range of glycosidases.     

Studies on Nepalese crude drugs. XXIX. Chemical constituents of Dronapuspi, the whole herb of Leucas cephalotes SPRENG

From the whole herb of Leucas cephalotes SPRENG., new labdane-, norlabdane- and abietane-type diterpenes named leucasdins A (1), B (2) and C (3), respectively, and two protostane-type triterpenes named leucastrins A (4) and B (5) were isolated, together with a known triterpene, oleanolic acid, five sterols, 7-oxositosterol, 7-oxostigmasterol, 7alpha-hydroxysitosterol, 7alpha-hydroxystigmasterol and stigmasterol, and eight flavones, 5-hydroxy-7,4'-dimethoxyflavone, pillion, gonzalitosin I, tricin, cosmosin, apigenin 7-O-beta-D-(6-O-p-coumaroyl)glucopyranoside, anisofolin A and luteolin 4'-O-beta-D-glucuronopyranoside. The structures of 1--5 were determined as (3S,6R,8R,9R,13S,16S)-9,13,15,16-bisepoxy-3,16-diacetoxy-6-formyloxylabdane, (3S,6R)-3-acetoxy-6-formyloxy-iso-ambreinolide, (4R,9S,12R,13R)-12,13-dihydroxyabiet-7-en-18-oic acid, (3S,17S,20S,24S)-3,20-dihydroxy-24-methylprotost-25-en, and (3S,17S,20S,24S)-3,20,24-trihydroxyprotost-25-en respectively, based on spectral and chemical data.     

Pseurotin, a new metabolite of Pseudeurotium ovalis Stolk having an unusual hetero-spirocyclic system.

The structure and absolute configuration of pseurotin ( 1 ), a new metabolite, isolated from culture filtrates of Pseudeurotium ovalis STOLK (Ascomycetes), has been shown to be 2-[1′(S), 2′ (S)-dihydroxhex-3′-ene-yl]-3-methyl-8(S)-methoxy-8-benzoyl-9(R)-hydroxy-(5S)-1-oxa-7-aza-spiro[4.4]non-2-ene-4, 6-dione ( 1 ), by spectral data and chemical transformations, and by X-ray analysis of its dibromo derivative 2 [1].     

含杂环卡宾碳的铁羰基簇合物的结构化学研究Ⅱ．—Fe_3(CO)_8[:CNHC(S)C(CH_3)_2NH]的合成和晶体结构

Ｆｅ３（ＣＯ）＿（１２）和取代２，４＿二硫代乙内酰脲反应，得到新的取代物Ｆｅ３（ＣＯ）＿８－［：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ＿３）＿２ＮＨ］（μ＿３－Ｓ）＿２，并进行了ＩＲ、１￣ＨＮＭＲ、ＭＳ表征，测定了它的分子和晶体结构，讨论了杂环卡宾碎片：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ＿３）＿２ＮＨ的取代位置，它是通过卡宾碳原子与Ｆｅ配位。     

Diastereoselective tandem Michael-intramolecular Wittig reactions of a cyclic phosphonium ylide with 8-phenylmenthyl enoates.

The diastereoselective tandem Michael-intramolecular Wittig reactions of a five-membered cyclic phosphonium ylide 2 using 8-phenylmenthyl enoates were examined. The reaction of the phosphonium ylide with 8-phenylmenthyl cinnamate followed by the hydrolysis of the resulting enol ether 4a afforded (3R,4S)-4-(diphenylphosphinyl)-3-phenylcycloheptanone (3R,4S)-5a as the major isomer. The diastereoselectivity of the initial tandem reactions was estimated to be 94:6 from the 31P NMR of a mixture of the diastereomeric ketal derivatives 6a and 6'a which were obtained by the reaction of 5a with (2R,3R)-2,3-butanediol, and the absolute configuration of the major isomer was determined by the single-crystal X-ray analysis. Similar reactions using some 8-phenylmenthyl alkenoates were attempted. As a result, it was clarified that the corresponding trans-ketones 5b-d were obtained and that the diastereomer ratios of their ketal derivatives were 60:40-73:27.     

The enantioselective metabolism of p-cymene in rabbits.

p-Cymene (1) was metabolized in rabbits and the following four optically active metabolites, 2-(p-tolyl)-1-propanol (3': R/S = 65:35), 2-(p-tolyl)propanoic acid (5': R/S = 0:100), p-(2-hydroxy-1-methylethyl)benzoic acid (6': R/S = 91:9) and p-(1-carboxyethyl)benzoic acid (8': R/S = 30:70), were isolated in addition to three optically inactive metabolites, 2-(p-tolyl)-2-propanol (2), p-isopropylbenzoic acid (4'), and p-(1-hydroxy-1-methylethyl)benzoic acid (7'). The presumed metabolic pathways of p-cymene in rabbits were confirmed by the administration of the intermediate metabolites (2, 3', 4', and 5'). The enantiomeric ratios of the metabolites, 3' and 6', suggested that omega-hydroxylations of the isopropyl group in 1 and 4' occurred preferentially at the pro-S methyl group. In the metabolism of 1, the S-isomers are predominant in the propanoic acid derivatives, but the R-isomers are rich in the propanol derivatives. It is of interest that the metabolism of 4', however, produced predominantly the corresponding propanol derivative (6'; R/S = 91:9) and propanoic acid derivative (8'; R/S = 80:20) possessing the same R-configuration. Some optically active p-cymene derivatives were also synthesized as standard compounds.     

Studies of the constituents of Gardenia species. II. Terpenoids from Gardeniae Fructus

Four new terpenoids, gardenate A (1), 2-hydroxyethyl gardenamide A (2), (1R,7R,8S,10R)-7,8,11-trihydroxyguai-4-en-3-one 8-O-beta-D-glucopyranoside (3) and Jasminoside F (4), were isolated from Gardeniae Fructus. Their structures were established on the basis of spectral analysis.     

Evidence of desulfurization in the oxidative cyclization of thiosemicarbazones. Conversion to 1,3,4-oxadiazole derivatives

The addition of pyridine-2-carbaldehyde 4N-methylthiosemicarbazone (C8H10N4S) to an aqueous solution of copper(II) nitrate yields [[Cu(C8H9N4S)(NO3)]2] (1). This complex consists of centrosymmetric dinuclear entities containing square-pyramidal copper(II) ions bridged through the sulfur thioamide atoms. The oxidation of 1 with KBrO3 or KIO3 gives rise to a compound with formula [[Cu(C8H8N4O)(H2O)2(SO4)]2]*2H2O (2) (C8H8N4O = 2-methylamino-5-pyridin-2-yl-1,3,4-oxadiazole). The structure of 2 is made up of centrosymmetric dimers where the copper(II) ions exhibit a distorted octahedral coordination and are connected by the oxadiazole moiety. The metal ions in 2 can be removed by addition of K4[Fe(CN)6], and then the oxadiazole ligand can be isolated and recrystallized as (C8H8N4O)*3H2O (3).