The Isolation,Structure, and Synthesis of Davana Ether,an Odoriferous Compound of the Oil of Artemisia pallens Wall.

Several stereoisomers of 2,6,10-trimethyl-2:5, 7:10-diepoxy-dodeca-3,5,11-triene ( 3 ) have been isolated from the oil of Artemisia pallens. The synthesis of the isomeric mixture is described.     

Ultra-low temperature oxidation of 5,6-dihydroxyindole: a novel approach to study synthetic melanogenesis

The detailed structure of melanin remains elusive due to the complexity and insolubility of the pigment. Herein we describe a novel oxidation of 5,6-dihydroxyindole (DHI) as a means to characterize soluble intermediates formed prior to oligomerization. The approach entails the use of a biomimetic copper-peroxo oxidant, at ultra-low temperature (-78 degrees C). DHI oxidized by [LCuII(O2)CuIIL]B(C6F5)4 (L=2,6,10-trimethyl-2,6,10-triazaundecane) under argon produces the one electron oxidation product, semiquinone radical, which is spectroscopically observed at -78 degrees C. MS analysis of the reaction mixture reveals the DHI dimer as well as other extensively oxidized DHI units.     

Terpenoids Derived from Linalyl Oxide. Part 1. The stereochemistry of the davanones

Natural (+)-davanone is 6S,7S,10R-2,6,10-trimethyl-7,10-oxidododeca-2,11-dien-5-one ( 1 ). Equilibration of davanone with base leads to the four possible isomers, but only a single deuterium atom is exchanged when deuterium oxide is the solvent.     

Negative-ion mass spectrometry and stereochemistry of organic compounds

Conclusions The ester group has a decisive role in the fragmentation process of the molecular negative ion following dissociative electron capture by the ethyl esters of isomeric 3,7,11-trimethyl-2,6,10-dodecatriene- and 10-oxo-3, 7-dimethyl-2,6-decadienecarboxylic acids.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 330–335, February, 1981.     

Five-coordinate nickel(II) complexes with carboxylate anions and derivatives of 1,5,9-triazacyclododec-1-ene: structural and 1H NMR spectroscopic studies

The hydroxo complexes [Ni2(mcN3)2(mu-OH)2]2(PF6)2[mcN3 = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me3-mcN3) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me4-mcN3)] react with the corresponding carboxylic acid [HA = benzoic (Hbz), salicylic (Hsal) or acetylsalicylic (Hacsal) acid] to give five-coordinate nickel(II) complexes of the type [Ni(mcN3)(A)](PF6). The complexes have been studied by spectroscopic methods (IR, UV-Vis and 1H NMR). In acetone solution they exhibit isotropically shifted 1H NMR resonances. The full assignment of these resonances has been made using one- and two-dimensional 1H NMR techniques. The single-crystal structures of [Ni(Me4-mcN3)(bz)](PF6), [Ni(Me4-mcN3)(sal)](PF6) and[Ni(Me4-mcN3)(acsal)](PF6) have been established by X-ray diffraction.     

Reactivity of fused 1,3-benzothiaphospholes: Formation of pentacoordinated derivatives

Fused 1,3-benzothiaphospholes 2 (cis-2,6,10-trimethyl-[1, 3]benzothiaphospholo[2,3-b][1, 3]benzothiaphosphole) reacts with H₂O₂ and S₈, giving the corresponding oxide and sulfide, respectively. The reactions of 2 with diethyl azodicarboxylate (DEAD)/catechol or DEAD/o-aminophenol, o-azidophenol, and tetrachloro-o-benzoquinone (TOB) give the first examples of spiro pentacoordinated phosphorus derivatives of this heterocyclic system. The X-ray structural analysis of spiro compound 3 showed a trigonal bipyramidal configuration at phosphorus in which the three rings assume axial-equatorial positions.     

空气稳定的氮杂蔻电子传输材料分子设计及三氮杂蔻衍生物迁移率计算

采用密度泛函理论研究氮功能化对蒄类化合物几何构型、电子结构及载流子传输性质的影响. 结果表明, 引入杂N原子可以线性降低前线轨道能级, 增强电子注入能力与空气稳定性, 且邻位掺杂较迫位和均匀掺杂调节效果更为显著. 其中, 十二氮杂蒄（12ac）具有新颖的“碗状”构型和高的电子亲和势（3.45 eV）, 是潜在的空气稳定电子传输材料构筑单元. 理论预测室温下2,6,10-三对甲氧基苯基-3,4,7,8,11,12-六甲氧基三氮杂蒄（3b）晶体的电子迁移率为0.242 cm2/V s, 预计是良好的电子传输材料, 值得进一步器件化研究.     

Quorum sensing in Candida albicans: probing farnesol's mode of action with 40 natural and synthetic farnesol analogs

The dimorphic fungus Candida albicans produces extracellular farnesol (3,7,11-trimethyl-2,6,10-dodecatriene-1-ol) which acts as a quorum-sensing molecule (QSM) to suppress filamentation. Of four possible geometric isomers of farnesol, only the E,E isomer possesses QSM activity. We tested 40 natural and synthetic analogs of farnesol for their activity in an N-acetylglucosamine-induced differentiation assay for germ tube formation (GTF). Modified structural features include the head group, chain length, presence or absence of the three double bonds, substitution of a backbone carbon by S, O, N, and Se heteroatoms, presence or absence of a 3-methyl branch, and the bulkiness of the hydrophobic tail. Of the 40 compounds, 22 showed QSM activity by their ability to reduce GTF by 50%. However, even the most active of the analogs tested had only 7.3% of the activity of E,E-farnesol. Structure-activity relationships were examined in terms of the likely presence in C. albicans of a farnesol binding receptor protein.     

Coordination to metal centers: a tool to fix high energy conformations in organic molecules. Application to 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene and related macrocycles

The solid state conformational preferences of ligand 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (L1) and its 9-methyl derivative (L2) in transition metal complexes have been determined by a probabilistic method using data retrieved from the Cambridge Structural Database. These macrocyclic compounds, as ligands, tend to adopt a preferential conformation (85% of cases). The ring containing the C=N bond adopts a distorted half-chair conformation, the ring defined by both the N-sp(3) shows a distorted envelope conformation, and the remaining ring exhibits a chair conformation. This conformation corresponds to the enantiomer pair R(N5)S(N9)S(P)/S(N5)R(N9)R(P). Molecular mechanics calculations demonstrate that this is a high energy conformation for the organic molecule, far from the energy minimum. Two other enantiomer pairs are observed in experimental structures. The influence of the coordination on the conformation of the organic ligands has been studied by DFT calculations, and a clear correlation with the geometry of the coordination sphere has been found.     

Synthesis and magnetic properties of nickel(II) triazamacrocyclic complexes. Crystal structure of [Ni(Me3[12]N3)(O2N)(H2O)]-(ClO4)·2H2O

Summary The synthesis, properties and X-ray crystal structure of [Ni(Me₃[12]N₃)(O₂N)(H₂O)](ClO₄)·2H₂O, in which Me₃[12]N₃ is 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene, are described. The Ni atom is octahedrally coordinated to three N atoms of the macrocycle, two O atoms of the nitrito group and one H₂O molecule. Monomeric units are linked by hydrogen bonds through one of the water of crystallization molecules, forming a chain. Magnetic measurements between 290 and 4 K reveal slight antiferromagnetic behaviour.     

Preparative High-Performance Liquid Chromatographic Separation of Natural Farnesol Isomers (1)

Abstract

Farnesol, 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol, is a naturally occurring sesquiterpenoid that is used in perfumery and synthesis. In synthesis, it is used as a starting material for other terpenoids and insect juvenile hormone derivatives. A preparative high-performance liquid chromatographic separation procedure was developed whereby 2.1 g of 2E,6E-farnesol could be readily isolated from 4.8 g of a 1:1 mixture of the 2E,6E- and 2Z,6E-isomers of farnesol. This rapid one-step procedure simplifies the separation of the mixed isomers on a preparative scale.     

Oxidative transformations of alkyl caryophyllanyl sulfides

Sesquiterpene sulfoxides and sulfones were synthesized in up to 56 and 74% yields, respectively. The oxidation of sulfides was accompanied by rearrangement of the epoxide fragment to allylic alcohol with subsequent oxidation. The isomerization of 4,5-epoxycaryophyllane-15-thiol afforded for the first time 4,11,11-trimethyl-8-(sulfanylmethyl)bicyclo[7.2.0]undec-3-en-5-ol in 40–45% yield.     

固相微萃取-气相色谱-质谱法鉴别海南黄花梨木与越南黄花梨木

采用固相微萃取-气相色谱-质谱法(SPME-GC-MS)研究了海南黄花梨木与越南黄花梨木中的挥发性成分,并对二者进行了鉴别。用电钻在黄花梨木上钻取少量粉末,采用SPME富集挥发性成分,经AB-FFAP极性毛细管气相色谱柱分离,共鉴定出20种挥发性成分,并发现了可用于鉴别海南黄花梨木与越南黄花梨木的两对特征成分:2-(1,1-二甲基乙基)-5-庚基-5-甲基-1,3-二氧戊环-4-酮与2,6,10-三甲基-7,10-环氧-2,11-十二碳二烯-6-醇、2-甲基亚丁基-环戊烷与2-(5-甲基-2-呋喃基)丙醛,并利用其相对含量的关系对海南黄花梨木与越南黄花梨木进行鉴别。该方法具有样品用量小、操作简便快速、不损害整体结构等特点,可用于黄花梨木挥发性成分的分析研究,亦适用于海南黄花梨木与越南黄花梨木的树种鉴别,在家具、工艺品及原木等的鉴别中具有广泛的应用前景。     

Synthesis of mesocyclic and macrocyclic polythioethers using the cesium dithiolate technique

The mesocyclic trithioethers, 1,4,7-trithiacyclodecane, 1,4,7-trithiacycloundecane, 1,4,8-trithiacycloundecane, and 1,5,9-trithiacyclododecane; the mesocyclic trithioether ketones, 1,4,7-trithiacyclodecan-9-one; 1,4,8-trithiacycloundecan-6-one, and 1,5,9-trithiacyclododecan-3-one; and the mesocyclic trithioether alcohols, 1,4,7-trithiacyclodecan-9-ol, 1,4,8-trithiacycloundecan-6-ol, and 1,5,9-trithiacyclododecan-3-ol, have been synthesized using the cesium dithiolate technique. In some cases, the corresponding macrocyclic hexathioether was isolated from the reaction mixture in addition to the mesocyclic trithioether; 1,4,7,11,14,17-hexathiacycloeicosane, 1,4,7,11,14,17-hexathiacycloeicosan-9,19-dione, 1,4,7,12,15,18-hexathiacyclodocosane, and 1,5,9,13,17,21-hexathiacyclotetracosane. Single-crystal X-ray structures have been determined for 1,5,9-trithiacyclododecan-3-ol and 1,4,7,12,15,18-hexathiacyclodocosane. For 1,5,9-trithiacyclododecane-3-ol, the compound crystallizes in the monoclinic space group, C2/c, with a = 10.5926( 9 ) Å, b = 15.582(2) Å, c = 13.6015(8) Å, β = 98.186(6)⁰, Z = 8, and R = 0.038. The macrocycle, 1,4,7,12,15,18-hexathiacyclodocosane, crystallizes in the orthorhombic space group, Pbca, with a = 21.406(5) Å, b = 9.810(2) Å, c = 10.225(2) Å, Z = 4, and R = 0.020.     

Synthesis of some cycloundecane derivatives from 1,5,9-cyclododecatriene

Summary Cycloundecanecarboxylic and cycloundecadienecarboxylic acids were synthesized from cis-trans-trans-1,5,9-cyclododecatriene.     

Preparation,crystal structures and NMR characterization of substituted-benzoate complexes Nickel(II)-N3-macrocycles

Substituted-benzoate complexes of nickel(II) of the types bidentate [Ni(mcN₃)(Bz)](PF₆) and monodentate [Ni(mcN₃)(Bz)(H₂O)](PF₆) have been prepared by acid-base reaction between the hydroxo complexes [Ni(mcN₃)(μ-OH)]₂(PF₆)₂ (mcN₃ = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me₃-mcN₃) or its 9-methyl derivative (Me₄-mcN₃)) and the corresponding benzoic acid. The paramagnetic nickel(II) complexes have been characterized in solution by NMR spectroscopy. The influence of the substituents on the hyperfine shift patterns for substituted-benzoate complexes of nickel(II) has been studied. The substituent effects upon the coordination mode of substituted benzoates have been established by X-ray diffraction.     

Chemo-enzymatic syntheses of drimane-type sesquiterpenes and the fundamental core of hongoquercin meroterpenoid by recombinant squalene-hopene cyclase

Squalene-hopene cyclase (SHC) converts squalene (C(30)) into pentacyclic triterpenes of hopene and hopanol. A linear sesquiterpene, (6E,10E)-2,6,10-trimethyldodeca-2,6,10-triene, underwent cyclization catalyzed by SHC, affording the following six bicyclic sesquiterpenes (drimane skeleton) in relatively high yield (68%): drim-7(8)-ene, drim-8(12)-ene, drim-8(9)-ene, driman-8α-ol, driman-8β-ol, and the novel sesquiterpene, named quasiclerodane, the skeleton of which is analogous to that of clerodane diterpene. To extend the scope of the enzymatic syntheses, acyclic sesquiterpenes to which a phenol moiety was appended were subjected to the enzymatic reaction catalyzed by SHC. The cyclic meroterpene core present in hongoquercins A and B was successfully prepared. The formation mechanisms of drimane-type sesquiterpenes and the cyclic meroterpene core of hongoquercins A and B are discussed.     

Synthesis of 1, 10-dec anedicarboxylic acid from cyclododecatriene-1,5,9

Summary A simple synthesis of 1,10-decanedicarboxylic acid has been developed, starting from cyclododecatriene-1,5,9.     

Syntheses, conformations, and basicities of bicyclic triamines

The multistep syntheses of several bicyclic triamines are described, all of which have an imbedded 1,5,9-triazacyclododecane ring. In 1,5,9-triazabicyclo[7.3.3]pentadecanes 12, 13, 15, and 16, two nitrogens are bridged by three carbons. The monoprotonated forms of these triamines are highly stabilized by a hydrogen-bonded network involving the bridge and both bridgehead nitrogens, producing a difference of more than 8 pK(a) units in acidities of their monoprotonated and diprotonated forms. The one- and zero-carbon bridges in 1,5,9-triazabicyclo[9.1.1]tridecane (23) and 7-methyl-1,5,9-triazabicyclo[5.5.0]dodecane (39) do not enhance the stabilities of their monoprotonated forms. X-ray crystal structures and computational studies of 12.HI and 16.HI reveal similar, but somewhat weaker, hydrogen-bonded networks, relative to 15.HI. The activation free energies for conformational inversion of 13.HI (14.4 +/- 0.2 kcal/mol), 16.HI (15.0 +/- 0.1 kcal/mol) and 16 (8.8 +/- 0.3 kcal/mol) were measured by variable-temperature (1)H and (13)C NMR spectroscopy. These experimental barriers give an estimate of 6.2 kcal/mol for the strength of the bifurcated hydrogen bond between the bridge nitrogen and cavity proton in 16.HI. Computational studies support the hypothesis that N-inversion occurs in an open conformation, leading to an estimate of 10.32 kcal/mol for the enthalpy of the bifurcated hydrogen bond in 16.HI in the gas phase.     

Synthesis and structural studies of hydrophilic mesocyclic trithioethers

The functionalized mesocyclic trithioethers, 1,4,7-trithiacyclodecane-9,9-dimethanol (10S3-diMeOH), 9 -methyl-1, 4, 7 - trithiacyclodecane - 9 -carboxylic acid (Me-10S3-acid), 1,4,7-trithiacycloundecane-9,10-diol (dihydroxy-11S3), 1,5,9-trithiacyclododecane-3,3-dimethanol (12S3-diMeOH), 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid (Me-12S3-acid), and 1 , 5 , 9 - trit hiacyclo tride cane -11 , 12 - diol ( dihydroxy - 13S3), have been synthesized using the cesium dithiolate technique. The single-crystal X-ray structure has been determined for 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid. The compound crystallizes in the monoclinic space group P2₁/n, with a = 9.513(2) Å, b = 5.706(1) Å, c = 25.70(1) Å, β = 96.50(1)°, Z = 4, and R = 0.075. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:123–128, 1998