Synthesis of optically active forms of seudenol,the pheromone of douglas fir beetle

(R)-(+)-Seudenol (3-methylcyclohex-2-en-1-ol) and its antipode were synthesized from optically active forms of 3-iodocyclohex-2-en-1-ol by treatment with Me₂CuLi. Their absolute configurations were determined by converting (+)-3-iodocyclohex-2-en-1-ol to the known (R)-(+)-cyclohex-2-en-1-ol.     

Excess molar volumes of (ethyl formate or ethyl acetate + an isomer of hexanol) at 298.15 K

Excess molar volumes V_m^E were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The V_m^E values were all positive, decreasing with the n value of the ester: C_n?1H_2n?1CO₂C₂H₅.     

Massenspektrometrische Untersuchungen von Terpenen

Zusammenfassung Die Massenspektren von acht Caranolen (trans-Caran-trans-2-ol, cis-Caran-trans-2-ol, trans-Caran-trans-3-ol, cis-Caran-trans-3-ol, trans-Caran-cis-3-ol, cis-Caran-cis-3-ol, Caran-trans-4-ol und Caran-cis-4-ol) wurden untersucht. Aus der Zuordnung der metastabilen Ionen ergaben sich Hinweise auf den Mechanismus der Fragmentierung von Caranol-Ionen. Ein Vergleich der Massenspektren zeigte, da\ die quantitativen Unterschiede in den relativen IntensitÄten sowohl eine qualitative Identifizierung als auch eine quantitative Analyse von Caranolgemischen erlauben.

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Summary The mass spectra of eight caranols (trans-carane-trans-2-ol, cis-carane-trans-2-ol, trans-carane-trans-3-ol, cis-carane-trans-3-ol, trans-carane-cis-3-ol, cis-carane-cis-3-ol, carane-trans-4-ol, and carane-cis-4-ol) were investigated. Certain aspects of the caranol ion fragmentation mechanism could be derived from an analysis of metastable ions. It is concluded that identification of caranols as well as quantitative analysis of caranol mixtures can be based solely on quantitative evaluation of abundance ratios.

     

长枝沙菜乙醇-乙酸乙酯溶出物的化学成分

海洋药物具有显著的药理稳定性和强效性,毒副作用相对较小,对防治癌症、艾滋病、心脑血管病、老年病等疑难杂症具有独特的作用,已成为开发新药、特效药的主要方向之一。长枝沙菜(Hyphea Charoides Lamx.)属红藻门沙菜科,其微量元素含量丰富。本文首次对长枝沙菜的化学成分进行了研究,从中分离得到神经酰胺和甾醇两类具有较强生理活性的物质。     

Oxidation of alcohols by chlorine dioxide in organic solvents

The kinetics of oxidation of a series of alcohols (propan-2-ol, 2-methylpropan-1-ol, butan-1-ol, butan-2-ol, 3-methylpentan-1-ol, heptan-4-ol, decan-2-ol, cyclohexanol, borneol) by chlorine dioxide in organic solvents was studied using spectrophotometry. The reaction is described by the second-order rate equation w = k[ROH][ClO₂]. The rate constants were measured in the range of 10–60 °C, and the activation parameters of the processes were calculated. The products were identified, and the yields were determined.     

Synthesis of New 3-Phenoxypropan-2-ols with Various Heterocyclic Substituents

1-Phenoxy-3-piperidinopropan-2-ol, 1-(5-methyl-1,3-benzothiazol-2-ylsulfanyl)-3-phenoxypropan-2-ol, 1-(2-hydroxy-3-phenoxypropyl)azepan-2-one, 1,1′-(6-chloro-1,3-benzothiazol-2-ylimino)bis(3-phenoxypropan-2-ol), 1-(1,3-benzothiazol-2-ylsulfanyl)-3-phenoxypropan-2-ol, 1,1′-(piperazine-1,4-diyl)bis(3-phenoxypropan-2-ol), and 1,3-bis(2-hydroxy-3-phenoxypropyl)barbituric acid were synthesized by condensation of 1,2-epoxy-3-phenoxypropane with the corresponding amines and thiols.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 70–72.Original Russian Text Copyright © 2005 by Mesropyan, Ambartsumyan, Avetisyan, Galstyan, Arutyunova.     

Hydroxylation of dammarane type triterpenes with m-chloroperbenzoic acid

Dammaran-20(S)-ol and 20(S)-hydroxydammaran-3β-yl acetate were reacted with $\text{m}$-CPBA to give the corresponding 5α-ol, 7β-ol, 12β-ol, 25-ol, 2α-ol, and 5α,25-diol.     

Heck reactions of aryl bromides with alk-1-en-3-ol derivatives catalysed by a tetraphosphine/palladium complex

cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C₃H₅)]₂ efficiently catalyses the Heck reaction of alk-1-en-3-ol with a variety of aryl bromides. In the presence of hex-1-en-3-ol or oct-1-en-3-ol, the β-arylated carbonyl compounds were selectively obtained. Linalool and 2-methylbut-3-en-2-ol led to the corresponding 1-arylalk-1-en-3-ol derivatives. Turnover numbers up to 69,000 can be obtained for this reaction. A minor electronic effect of the substituents of the aryl bromide was observed. Similar reaction rates were observed in the presence of activated aryl bromides such as bromoacetophenone and deactivated aryl bromides such as bromoanisole.     

Kinetic scheme of homogeneous acid-catalyzed transformation of isopentenols

The reactions occurring in an equilibrium mixture of 3-methyl-1-buten-3-ol and 3-methyl-2-buten-1-ol in 24–49 % aqueous solutions of H₂SO₄ yield isoprene, 3-methyl-3-buten-1-ol, isobutylene, formaldehyde, 3-methylbutane-1,3-diol. Isobutylene is rapidly hydrated to give 2-methylpropan-2-ol. The presence of formaldehyde in the reaction mixture indicates that the transformations involve the reverse Prins reaction. On the basis of experimental and literature data, two most probable reaction schemes were suggested.Translated fromIzvestiya Akademii Nauk. Sertya Khimicheskaya, No. 5, pp. 867–870, May, 1995.     

Reaction of Grignard Compounds with 4-Chloro-2-methyl-3-butyn-2-ol in Diethyl Ether Equivalents

Reactions of RMgX·THF complexes with 4-chloro-2-methyl-3-butyn-2-ol in aromatic hydrocarbons were studied. The complexes formed by arylmagnesium halides require the presence of anisole for the reaction to occur. 4-Chloro-2-methyl-3-butyn-2-ol can be synthesized by reaction of 2-methyl-3-butyn-2-ol with sodium hypochloride in the two-phase system water-benzene.     

Dehydration of ethylenic alcohols

Summary A systematic study was made of the catalytic dehydration of 4-methyl-1-penten-3-ol (Ia), 3,4-dimethyl-1--penten-3-ol (Ib), 3-isopropyl-4-methyl-1-penten-3-ol (Ic), 2-methyl-4-penten-2-ol (II), 2-methyl-3-penten-2-ol (III), 4-methyl-3-penten-2-ol (IV), and 2-methyl-4-hexen-3-ol (V). In the course of this study methods were developed for the preparation of the following substituted gem-dimethylbutadienes: 4-methyl-1,3-pentadiene (VIII), 3,4-dimethyl-1,3-pentadiene (IX), 2-methyl-2,4-hexadiene (XI), and 3-isopropyl-4-methyl-1,3-pentadiene (XIV).     

Changes of flavan-3-ols with different degrees of polymerization in seeds of 'Shiraz', 'Cabernet Sauvignon' and 'Marselan' grapes after veraison

Flavan-3-ols consist of flavan-3-ol monomers and polymers with different degrees of polymerization (DP). In this study, flavan-3-ol extracts from grape seeds were well separated into three fractions including monomers, oligomers (2 < DP < 10) and polymers (DP > 10), by means of normal-phase HPLC-MS. The different patterns of these three fractions were analyzed in three Vitis vinifera cultivars ('Shiraz', 'Cabernet Sauvignon' and 'Marselan') seeds from veraison to harvest. The results showed: (1) polymers were the main form of flavan-3-ols in grape seeds and monomers accounted for only a small proportion; (2) the contents of flavan-3-ol monomers in the seeds of three grape cultivars all exhibited a gradually decreasing trend with a little fluctuation, whereas the patterns of the change of contents of oligomers and polymers were extremely different among grape cultivars; the contents of flavan-3-ol oligomers were enhanced in the seeds of 'Cabernet Sauvignon', but were reduced in the other two cultivars; (3) with regard to the proportion of flavan-3-ols with a certain DP to total flavan-3-ols, both flavan-3-ol monomers and flavan-3-ols with low DP fell in proportion, while the flavan-3-ols with high DP increased correspondingly. These findings indicate that flavan-3-ol polymerization in developing seeds is variety-dependent and may be genetically regulated.     

Stereoisomeric Separation of Derivatized 2-alkanols Using Gas Chromatography-Mass Spectrometry: Sex Pheromone Precursors Found in Pine Sawfly Species

Stereoisomers of long-chain secondary alcohols are used as sex pheromone precursors among pine sawflies and some species can be severe pine forest pests. To use their pheromone in environmentally friendly pest management, methods are needed that can determine the stereochemistry of the precursor alcohols. Combinations of 11 acid chloride derivatives and 10 GC columns were evaluated for separation of stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, 3,7-dimethyltridecan-2-ol, 3,7-dimethyltetradecan-2-ol, and 3,7-dimethylpentadecan-2-ol. Derivatization with (S)-2-acetoxypropionyl chloride in combination with a Chiraldex B-PA column separated all eight stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, and 3,7-dimethyltridecan-2-ol. A combination of two different derivatization methods was needed to separate all stereoisomers of the longer chained alcohols 3,7-dimethyltetradecan-2-ol and 3,7-dimethylpentadecan-2-ol. A female extract of the pine sawfly Neodiprion lecontei was also analyzed and the stereochemistry of the sex pheromone alcohol precursor was determined to be (2S,3S,7S)-3,7-dimethylpentadecan-2-ol at an amount of about 7 ng/female. This paper presents the first GC-MS separation of all eight stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, and 3,7-dimethyltridecan-2-ol in a single analytical run and also the first GC-MS determination of the stereochemistry of the sex pheromone precursor found in females of N. lecontei.     

Viscosity of aqueous solutions of 2-propyne-1-ol, 2-methyl-3-butyne-2-ol and 3-butene-2-ol

Viscosities of aqueous solutions of 2-propyne-1-ol (propargyl alcohol), 2-methyl-3-butyne-2-ol and 3-butene-2-ol have been measured at temperatures 308.15, 313.15, 318.15, 323.15 and 328.15?K over the entire composition range. Viscosity of the aqueous solutions of 2-methyl-3-butyne-2-ol and 3-butene-2-ol increases up to a maximum value and then starts decreasing almost linearly as the mole fraction of alcohol increases. 2-Methyl-3-butyne-2-ol + water and 3-butene-2-ol + water systems exhibit maxima around 0.5 and 0.2 mole fraction, respectively. Conversely, 2-propyne-1-ol + water system shows a rapid initial increase in viscosity up to 0.3 mole fraction followed by a slow steady increase as the mole fraction of alcohol increases to its pure state. Plots of excess viscosities against mole fraction of organic solutes for all the systems exhibit a sharp increase in η ^E to reach a well defined maxima, after which the curves show a descending trend. The variations of viscosity and excess viscosity with the composition of the mixtures have been interpreted in terms of hydrophobic and hydrophilic interactions between the species forming the mixtures.     

CO2 laser-induced decomposition of propan-2-ol,butan-2-ol,pentan-2-ol,pentan-3-ol,and hexan-2-ol

The pulsed CO₂ laser-induced decompositions of propan-2-ol, butan-2-ol, pentan-2-ol, pentan-3-ol, and hexan-2-ol in the gas phase have been investigated. Like ethanol which we examined previously [1] the absorption cross section of propan-2-ol for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole-filling. In contrast the absorption cross section of butan-2-ol (10R24) has only a small pressure dependence and those of pentan-2-ol (9R26), pentan-3-ol (10R14), and hexan-2-ol (9P20) show little or no variation with pressure in the range 0.1–5.0 torr. Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and C? C fission channels, with minor contributions from other molecular eliminations. © 1994 John Wiley & Sons, Inc.     

Rates of reaction between the nitrate radical and some unsaturated alcohols

Rate coefficients for nitrate radical gas-phase reactions with prop-2-en-l-ol (allyl alcohol), but-1-en-3-ol, and 2-methylbut-3-en-2-ol have been determined. Both absolute (fast flow discharge with diode laser detection of NO₃) and relative (batch reactor and FTIR spectroscopy) rate techniques were used to measure the rate coefficients. The rate coefficients at 294 K are: (1.3 ± 0.2) × 10⁻¹⁴, (1.2 ± 0.3) × 10 ⁻¹⁴, and (2.1 ± 0.3) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ for prop-2-en-1-ol, but-1-en-3-ol, and 2-methylbut-3-en-2-ol, respectively. The activation energy for reaction of NO₃ with prop-2-en-1-ol was determined to 2.8 ± 2.5 kJ mol⁻¹ in the temperature range between 273 and 363 K. The atmospheric importance of unsaturated alcohols and structure-reactivity considerations are also discussed. © 1996 John Wiley & Sons, Inc.     

New synthetic method for 2,3-trans-2-methyl-tetrahydropyran-3-ol and oxepan-3-ol by unique insertion of a methyl group

Treatment of tetrahydropyran-3-ol and oxepan-3-ol derivatives, which have a 1′-mesyloxy group at the C-2 side chain, with Me₃Al effected removal of the mesyloxy group, 1,2-hydride shift, and stereoselective insertion of a methyl group into the resulting oxonium ion, giving 2,3-trans-2-methyl-tetrahydropyran-3-ol and oxepan-3-ol derivatives, respectively.     

Oxidation of higher alcanols by tetra-1-butylammonium permanganate

Summary Oxidations of hexan-1-ol, hexan-2-ol, hexan-3-ol, heptan-1-ol, heptan-2-ol, octan-1-ol, and octan-2-ol with tetra-1-butylammonium permanganate, dissolved in the same alcohols, proceed partly autocatalytically. The rate constants of both catalytic and non-catalytic reactions have been evaluated. Colloidal manganese dioxide, one of the reaction products, has been identified as the catalyst.

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Oxidation höherer Alkanole mit Tetra-1-butylammoniumpermanganat

Zusammenfassung Die Oxidation von 1-Hexanol, 2-Hexanol, 3-Hexanol, 1-Heptanol, 2-Heptanol, 1-Octanol und 2-Octanol durch Tetra-1-butylammoniumpermanganat, gelöst in diesen Alkoholen, verläuft teilweise autokatalytisch. Die Geschwindigkeitskonstanten von katalytischen und nichtkatalytischen Teilreaktionen wurden bestimmt. Das kolloidale Mangandioxid, eines der Reaktionsprodukte, konnte als Katalysator identifiziert werden.

     

Lewis acid catalysed rearrangement of triterpenoids

From the whole plant of Opuntia vulgaris Mill (Cactaceae), four known triterpenoids friedelin, friedelan, 3-ol, taraxerone and taraxerol, have been isolated. Friedelan 3β-ol and friedelan-3-ol undergo a novel rearrangement with boron tribromide. Taraxeryl-acetate gives the expected β-amyrin acetate which undergoes further reactions to δ-amyrin acetate. Friedelan 3β-ol rearranges on treatment with boron trifluoride to give mainly olean 13 (18)-ene and olean 12-ene, together with an unexpected epimeric product. Mechanisms are suggested for these various reactions.     

Enthalpic changes on mixing two couples of S- and R-enantiomers of heptane-2-ol, octane-2-ol, nonane-2-ol, 3-chloro-propane-1,2-diol, 2-methyl-1,4-butanediol at 298.15 K

Enthalpies of mixing of (R)- and (S)-enantiomers of liquid chiral compounds such as heptane-2-ol, octane-2-ol, nonane-2-ol, 3-chloro-propane-1,2-diol and 2-methyl-1,4-butanediol have been measured over a range of mole fractions at 298.15 K, albeit very small values. Mixing of heterochiral liquids of heptane-2-ol, octane-2-ol, nonane-2-ol, 3-chloro-propane-1,2-diol, realized enthalpic destabilization over the whole range of mole fractions, whereas that of 2-methyl-1,4-butanediol realized enthalpic stabilization over entire compositions. The maximum values of enthalpies of mixing and the intermolecular interaction of cohesive energy density and entropy of vaporization showed a linear correlation except for the compounds having two chiral centers and others.