Carbon-carbon double bond in pillar[5]arene cavity: Selective binding of cis/trans-olefin isomers

The binding behavior of pillar[5]arenes (P5As) towards a series of olefin guests ((E)-1,4-dichlorobut-2-ene (1E), (Z)-1,4-dichlorobut-2-ene (1Z), (E)-but-2-ene-1,4-diol (2E), and (Z)-but-2-ene-1,4-diol (2Z), as well as an alkyne derivative 1,4-dichlorobut-2-yne (3)) have been studied in organic solution. P5As exhibit considerable selectivities for the trans-olefin isomers (1E and 2E) over their cis-isomers (1Z and 2Z). The cis/trans-selective interactions hold the potential of utilizing P5As to separate olefin isomers.     

A study of 1,5-hydrogen shift and cyclization reactions of an alkali isomerized methyl linolenoate

Heating a mixture formed by alkali isomerization of methyl linolenoate (1) produces a complex mixture with the bicyclic hexahydroindenoic esters 4β-(7-methoxycarbonylheptyl)-5α-methyl-2,3,3aα,4,5,7aαhexahydroindene (CL5) and 4β-ethyl-5α-(6-methoxycarbonylhexyl)-2,3,3aα,4,5,7aα-hexahydroindene (CL6) as main components. Similar isomerization reactions of three synthetic model compounds, methyl 9Z,13E,15Z-octadecatrienoate (2), 9Z,14E,16E-octadecatrienoate (4) and 9Z,11E,15Z-octadecatrienoate (5) corroborated the results obtained with alkali isomerized methyl linolenoate.     

Oxidative degradation of eicosapentaenoic acid into polyunsaturated aldehydes

Eicosapentaenoic acid is converted in good overall yield to an α,β-ethylenic epoxide derivative. The oxidative cleavage of the epoxide ring with periodic acid in ether proceeded in part with acid-catalyzed rearrangement of the vinyl epoxide moiety prior to cleavage. Among the products were 2E- and 2Z, 5Z, 8Z, 11Z-tetradecatetraenal, 4-hydroxy-2E,6Z,9Z,12Z-pentadecatetraenal and (all-Z)-2-methoxy-3,6,9,12-pentadecatetraenal.     

Synthesis of deuterated 5(Z),11(Z)-eicosadienoic acid as a biomarker for trophic transfer

The poly-methylene interrupted fatty acid 5(Z),11(Z)-eicosadienoic acid and its tetradeuterated analogue were prepared via a convergent synthetic sequence.     

Reaction of trialkylboranes with 2-bromo-6-lithiopyridine: Stereospecific alkylative cleavage of pyridine ring

Reaction of 2-bromo-6-lithiopyridine with trialkylboranes affords 5-alkyl-5-dialkylboryl-2-(Z), 4(E)- pentadienenitriles by stereospecific alkylative cleavage of the pyridine ring. These intermediary vinylboranes are versatile reagents for the preparation of 5-alkyl-2(Z), 4(E)-pentadienenitriles, 5,5-dialkyl-4-pentenenitriles and 5,5-dialkyl-2,4-pentadienenitriles.     

Malyngic acid,a new fatty acid from Lyngbya majuscula

Malyngic acid, a major fatty acid in several varieties of the marine blue-green alga Lyngbya majuscula, has been determined to be 9(S),12(R),13(S)-trihydroxyoctadeca-10(E),15(Z)-dienoic acid from chemical and spectral data and by its conversion to 9(S),12(R),13(S)-trihydroxystearic acid and degradation to 2-deoxy-D-ribitol.     

Synthesis of E and Z 1-amino-2-aryl(alkyl)-cyclopropanecarboxylic acids via meldrum derivatives

The reaction of 5-arylidene(alkylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (1) (Meldrum's acid derivatives) with dimethylsulfoxonium methylide gave 1- aryl(alkyl) - 6,6 - dimethyl - 4,8 - dioxo - 5,7 -dioxaspiro [2.5] octanes (2) which, on treatment with sodium methoxide or ammonium hydroxide, gave exclusively E-1-methoxy-carboyl-2-aryl-cyclopropanecarboxylic acids (4) or Z-1-carbamoyl-2-aryl(alkyl)-cyclopropanecarboxylic acids (7), respectively. Compounds, 4, under conditions of Curtius-type reactions, yielded Z-methyl 1-isocyanate-2-aryl-cyclopropanecarboxylates (5), while derivatives 7 were treated with hypobromite, leading to E-1-methoxy-carbonylamino-2-aryl(alkyl)-cyclopropanecarboxylic acids (8).Reaction of compounds 5 and 8 with hydrochloric acid produced the corresponding Z and E 1-amino-2-aryl (alkyl)-cyclopropanecarboxylic acids hydrochlorides (6). The ¹H-NMR spectral data were analyzed to deduce the stereochemistry of the compounds obtained.     

A chiron approach to the cyclopropyl lactone oxylipins

Enantiomerically pure key intermediates for the synthesis of constanolactones A and B and solandelactones A, B, E and F, the hydroxy-protected (3S,5Z)-undec-1-yn-5-en-3-ol and (3S,1E,5Z)-1-iodoundec-1,5-dien-3-ol, have been obtained in nine steps starting from (S)-malic acid.     

Leiopathic Acid,a Novel Optically Active Hydroxydocosapentaenoic Acid,and related compounds,from the black coral Leiopathes sp. of Saint Paul Island (S. Indian Ocean)

The antipatharian Leiopathes sp., collected around Saint Paul Island, is shown here to contain, in relatively high amounts, the novel fatty acid leiopathic acid ( = (+)-(10R,7Z,11E,13Z,16Z,19Z)-10-hydroxy-7,11,13,16,19-docosapentaenoic acid; (+)- 1 ), besides (+)-(8R,5Z,9E,11Z,14Z,17Z)-8-hydroxy-5,9,11,14,17-icosapentaenoic acid ((+)- 11 ) and (+)-(8R,5Z,9E,11Z,14Z,)-8-hydroxy-05,9,11,14-icosatetraenoic acid ((+)- 16 ) and their ethyl ester (+)- 2 , (+)- 12 , and (+)- 17 .     

In situ alcohol oxidation-Wittig reactions using N-methoxy-N-methyl-2-(triphenylphosphoranylidine)acetamide: application to the synthesis of a novel analogue of 5-oxo-eicosatetraenoic acid

Benzylic, allylic, propargylic and unactivated alcohols can be oxidised with activated manganese dioxide in the presence of N-methoxy-N-methyl-2-(triphenylphosphoranylidine)acetamide to generate directly the corresponding α,β-unsaturated Weinreb amides. Elaboration of the resulting Weinreb amides is also described, in particular as part of a new route to analogues of the arachidonic acid metabolite 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid.     

Phenanthrenes from Juncus atratus with antiproliferative activity

The present study has focused on the isolation and structure determination of phenanthrenes from Juncus atratus Krock. Nine compounds, among them five phenanthrenes, have been isolated from the methanol extract of the plant. Two compounds [juncatrins A (1) and B (2)] are new natural products, three phenanthrenes [juncuenin B (3), effusol (4), and dehydroeffusol (5)], the flavones apigenin (7) and luteolin (8), the diterpene phytol and 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trien-oic acid (9) were isolated for the first time from the plant. Juncatrin A (1) is substitued with an acetyl group, while in case of juncatrin B (2), an unprecedented acetylene group is connected to the phenanthrene skeleton. The isolated phenanthrenes were evaluated for their antiproliferative activity against HeLa, SiHa and MDA-MB-231 human tumor cell lines. Four phenanthrenes (2, 3, 4 and 5) were more effective [IC₅₀s 3.48?μM (2), 2.91 (3), 3.68 (4), and 7.75?μM (5)] than cisplatin (IC₅₀ 12.43?μM) on HeLa cells.     

Total syntheses of four possible stereoisomers of resolvin E3

Resolvin E3, 17,18-dihydroxy-5Z,8Z,11Z,13E,15E-eicosapentaenoic acid, is a potent anti-inflammatory lipid mediator. To determine the stereochemistries of the C17- and C18-hydroxy groups of resolvin E3 and to supply a sufficient amount of material for future biological studies, we developed a highly convergent and practical route to its four possible stereoisomers. The key reactions employed here were the Horner–Wadsworth–Emmons coupling, the two copper(I)-mediated reactions between the alkynes and the propargyl tosylates, and the simultaneous reduction of the three triple bonds to the three Z-olefins.     

Metabolites identification of oil palm roots infected with Ganoderma boninense using GC–MS-based metabolomics

An approach to metabolomics profiling of non-infected and Ganoderma boninense (G. boninsense) infected oil palm roots crude extracts that utilize gas chromatography-mass spectrometry (GC–MS) and multivariate statistics of principal component analysis (PCA) have been tested. This combination has provided a rapid approach in investigating the changes in the metabolite variations of non-infected and infected oil palm roots at 14 and 30 days post-infection. The extracts were prepared by using 80% (v/v) of methanol. In identifying the metabolites responsible for each differentiation, PCA model was generated in loading bi-plot. Dimethyl benzene-1,4-dicarboxylate, methyl 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate, ergost-5-en-3-ol, (3β), stigmast-5-en-3-ol, (3β), stigmasterol, methyl hexadecanoate, methyl (9Z,12Z)-octadeca-9,12-dienoate, methyl octadecanoate, 2-(hydroxymethyl)-2-nitropropane-1,3-diol, methyl (Z)-octadec-6-enoate and (E)-icos-5-ene were found more abundant in G. boninense infected roots than in non-infected roots. Steroidal compounds and fatty acid derivatives which has been determined in the non-infected and G. boninense infected roots regulate a variety of responses to the G. boninense. The abundant of these metabolites in G. boninense infected roots are due to the crucial roles in pathogen defence.     

Reaction of 4-methylene-5(4H)-oxazolones with diazomethane

The reaction of diazomethane with some (E) and (Z)-2-substituted-4-methylene-5(4)-oxazolones ( 1a-c ) under two different conditions, has been studied. (E) and (Z)-1,2-disubstituted-7-oxo-6-oxa-4-azaspiro[2.4]-hept-4-enes ( 3a-c, 4a-c ) were mainly obtained, together with multiple addition compounds. The reaction showed to be stereoselective only when the substituents were aromatic. Acid hydrolysis of compounds 3a and 4a produced a mixture of (E) and (Z)-3,5-disubstituted-tetrahydrofuran-2-ones ( 8a, 9a ). Smooth methanolysis of the ring led to (E) and (Z)-1-benzamido-cyclopropanecarboxylic esters ( 10a-c, 11a-c ), which, on acid hydrolysis, gave (E) and (Z)-1-amino-2-phenylcyclopropanecarboxylic acids 12a and 13a . The pmr spectra have been analyzed by an iterative computer method, and the computed best values obtained have been used to deduce the stereochemistry of the spiroderivatives.     

Two new labdane diterpenoids from the rhizomes of Isodon yuennanensis

Two new labdane diterpenoids, s-trans-8(17),12E,14-labdatrien-20-oic acid (1), s-trans-12E,14-labdadien-20,8β-olide (2), along with 10 known compounds, hinokiol (3), ursonic acid (4), 2α,3α-dihydroxyolean-12-en-28-oic acid (5), 2α,3β,23-trihydroxyolean-12-en-28-oic acid (6), ethyl 3-(3,4-dihydroxyphenyl)lactate (7), ethyl rosmarinate (8), (Z,E)-2-(3,4-dihydroxyphenyl)ethenyl caffeic ester (9), tridecanoic acid (10), β-sitosterol (11) and daucosterol (12), were isolated from the 70% acetone extract of the rhizomes of Isodon yuennanensis. Their structures were elucidated based on the analyses of extensive spectroscopic data and physicochemical properties.     

Preparation of stereochemically pure <Emphasis Type="Italic">E</Emphasis>- and <Emphasis Type="Italic">Z</Emphasis>-alkenoic acids and their methyl esters from bicyclo[<Emphasis Type="Italic">n</Emphasis>.1.0]alkan-1-ols. Application in the synthesis of insect pheromones

Oxidative cleavage of exo- and endo-alkyl- and hydroxyalkyl-substituted bicyclo[n.1.0]alkan-1-ols with (diacetoxy-λ³-iodanyl)benzene gave the corresponding methyl alkenoates exclusively with E or Z configuration of the double bond. This reaction was used as the key stage in the syntheses of stereoisomerically pure components of pest insect pheromones: (E)-dodec-9-en-1-yl acetate (European pine shoot moth Rhyacionia buoliana), (Z)-tetradec-11-en-1-yl acetate (European oak leafroller Tortrix viridana), and (3E,8Z,11Z)-tetradeca-3,8,11-trien-1-yl acetate (tomato leafminer Tuta absoluta).     

Photochemie von in 4-Stellung substituierten 5-Methyl-3-phenyl-isoxazolen.44. Mitteilung über Photoreaktionen

Photochemistry of 4-substituted 5-Methyl-3-phenyl-isoxazoles. 4-Trideuterioacetyl-5-methyl-3-phenyl-isoxazole ([CD₃CO]- 27 ), upon irradiation with 254 nm light, was converted into a 1:1 mixture of oxazoles [CD₃CO]- 35 and [CD₃]- 35 (Scheme 13). This isomerization is accompagnied by a slower transformation of ([CD₃CO]- 27 ) into [CD₃]- 27 . Irradiation of the isoxazole derivatives 28, 29, 30 and (E)- 31 yielded only oxazoles 36, 37, 38 and (E), (Z)- 39 ; no 4-acetyl-5-alkoxy-2-phenyl-oxazole, 2-acetyl-3-methyl-5-phenyl-pyrrole or 2-acetyl-4-methoxycarbonyl-3-methyl-5-phenyl-pyrrole, respectively, were formed (Scheme 9 and 10). Similarly (E)- 32 gave a mixture of (E), (Z)- 40 only (Scheme 11). Upon shorter irradiation, the intermediate 2H-azirines (E), (Z)- 41 could be isolated (Scheme 11). Photochemical (E)/(Z)-isomerization of the 2-(trifluoro-ethoxycarbonyl)-1-methyl-vinyl side chain in all the compounds 32, 40 and 41 is fast. At 230° the isoxazoles (E)- and (Z)- 32 are converted into oxazoles (E), (Z)- 40 . The same compounds are also obtained by thermal isomerization of the 2H-azirines (E), (Z)- 41 . The most probable mechanism for the photochemical transformations of the isoxazoles, as exemplified in the case of the isoxazole 27 , is shown in Scheme 13. A benzonitrile-methylide intermediate is postulated for the photochemical conversion of the 2H-azirines into oxazoles. 2H-Azirines are also intermediates in the thermal isoxazole-oxazole rearrangement. It is however not yet clear, if the thermal 2H-azirine-oxazole transformation involves the same transient species as the photochemical reaction. A mechanism for the photochemical isomerization of the 2H-azirine 11 to the oxazole 15 is proposed (Scheme 3).     

Photochemistry of dienones—X: Photochemistry of (e)-β-ionone oxime ethyl ether

(E)-β-ionone oximc ethyl ether [(E, E)-4] upon direct irradiation with λ either254or 313 nm yields the geometrical isomer (E, Z)-4 and (Z)-retro-γ-ionone oxime ethyl ether (Z,E)-5 as the sole primary products, illustrating (E)-(Z) isomerization (φ₃₁₃ =0.49) and a 1, 5-hydrogen shift (φ313 =0.15) respectively. From studies with triplet photosensitizers and with ethyl iodide (to enhance the singlet-triplet intersystem crossing) it is concluded that these two products in the direct irradiation result only from the singlet excited state, and that the inter-system crossing quantum yield is relatively low. Upon prolonged irradiation of (E,E)-4 with λ 313 nm the eventual products are (Z,E)-5 and (Z,Z)-5, whereas with λ 254 nm they are (E,E)-5 and [(Z,E)-5 and/or (E,Z)-5]. Upon triplet photosensitization (E,E)-4 undergoes only (E)-(Z) isomerization, leading to a mixture of all the four geometrical isomers of4. From the dependence of the geometrical isomer distribution in the photostationary state on the triplet energy of the sensitizer the triplet energies of (E,E)-4, (E, Z)-4, (Z, E)-4, and (Z, Z)-4 have been determined to be ca 55, < 55,57, and 57 $\text{kcal}\text{mol}$ respectively.     

Synthesis of 2E,4E,6E,11Z-octadecatetraenoic acid of the Rhizobium leguminosarum biovar viciae Nod factor

2E,4E,6E,11Z-Octadecatetraenoic acid was synthesized in a good yield and in a stereospecific manner by coupling a vinylborane compound and ethyl trans-3-iodoacrylate. The trienic system (E,E,E) was obtained by successive use of metal-catalyzed coupling and hydro-metallation reactions.     

Stereoselective synthesis of insect sex pheromone analogs having a fluorine atom on their double bonds

Insect sex pheromone analogs having a fluorine atom on their double bonds, (9E,11E)-1-acetoxy-9-fluorotetradecadiene, (10E,12E)-13-fluorohexadecadien-1-ol, (9Z,11E)-1-acetoxy-9-fluorotetradecadiene, (10E,12Z)-13-fluorohexadecadien-1-ol were stereoselectively synthesized using cross-coupling reactions of alkenylboranes with (E)- or (Z)-2-fluoro-1-iodo-1-alkenes, stereoselectively prepared from 1-alkynes by our currently developed methods.