Volatiles from thermal decomposition of isomeric methyl (12S, 13S)-(E)-12,13-epoxy-9-hydroperoxy-10-octadecenoates

Two epimers of methyl (12S,13S)-(E)-12,13-epoxy-9-hydroperoxy-10-octadecenoate were isolated after esterification of a mixture of fatty acids obtained from decomposition of (13S)-(9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid by an Fe⁺⁺-cysteine catalyst. These epimeric epoxyhydro-peroxyoctadecenoates were decomposed by heat (210 C) in the injection port of a gas chromatograph, and the cleavage fragments were subsequently separated by gas chromatography (GC) and identified by mass spectrometry (MS). Among the scission products obtained, the most prominent in the GC peak profile were methyl octanoate and methyl 9-oxononanoate. Other peaks were identified as pentane, 1-pentanol, hexanal, 2-heptanone, 2-pentylfuran, methyl heptanoate, 2-octenal, 4,5-epoxy-2-decenal, methyl 8-(2-furyl)-octanoate, 11-oxo-9-undecenoate and methyl 13-oxo-9,11-tridecadienoate. In addition, 3,4-epoxynonanal, methyl 8-oxooctanoate, 3-hydroxy-2-pentyl-2,3-dihydrofuran and methyl 10-oxodecanoate were tentatively identified. Except for the furan compounds, the formation of the fragmentation products could be explained by conventional free-radical scission mechanisms. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Selective oxidations of methyl ricinoleate: Diastereoselective epoxidation with titaniumIV catalysts

Conditions were developed for the selective epoxidation of the double bond of methyl ricinoleate (1) with ethylmethyldioxirane (EMDO) to give the homoallylic epoxyalcohol, methyl (Z)-9,10-oxido-12-hydroxyoctadecanoate (2) in high yields but in poor enantiomeric excess. The diastereomeric ratio for epoxyalcohol 2 was improved modestly when t-butyl-hydroperoxide, coupled with a titanium catalyst and a d-tartrate ligand, was used as oxidizing agent. Reaction of 1 with excess EMDO resulted in the concomitant epoxidation of the double bond and oxidation of the hydroxy group of 1 to give methyl (Z/it)-9,10-oxido-12-oxo-octadecanoate (4), along with methyl 8-(5-hexylfuran-2-yl)octanoate (5). Alternatively, ketoepoxide 4 was prepared by dioxirane oxidation of methyl 12-oxo-(Z)-9-octadecene (3) or by treating epoxyalcohol 2 with sodium hypochlorite. The ketoepoxide 4 is acid-labile and rearranges with loss of water to give furan 5 in high yield. Presented in part at the 88th Annual Meeting, American Oil Chemists’ Society, Seattle, Washington, May 1997.     

Enzymatic hydrolysis of long-chainN-heterocyclic fatty esters

Incubation of a 1-pyrroline ester [viz. methyl 8-(5-hexyl-1-pyrroline-2-yl)octanoate,1] with bakers' yeast (Saccharomyces cerevisiae) gave the corresponding free fatty acid (1a, 52%). The C=N bond of the 1-pyrroline was not reduced by the yeast. Complete hydrolysis of compound1 was successful using lipase ofCandida cylindracea (CCL) or Lipolase (Rhizomucor miehei) under stirred or ultrasound condition. Fatty esters containing a pyrrolidine [viz. methyl 8-(cis/trans-5-hexyl-pyrrolidine-2-) octanoate,2] orN-methyl pyrrolidine [viz. methyl 8-(cis-5-hexyl-N-methyl-pyrrolidine-2-)octanoate,3] system in the alkyl chain were not hydrolyzed by either CCL or Lipolase, unless conducted in an ultrasonic bath. The hydrolytic activities of the enzymes appeared to be strongly affected by the stereochemistry of theN-heterocyclic ring system. Chemical hydrolysis of compounds1–3 gave the corresponding fatty acidN-HCl salts.     

Autoxidation of the furan fatty acid ester, methyl 9,12-epoxyoctadeca-9,11-dienoate

The objective of this study was to identify autoxidation products of methyl 9,12-epoxyoctadeca-9,11-dienoate (F_9,12). Previous work has shown that F_9,12 is a product both of autoxidation and singlet oxygen oxidation of the methyl ester derivative of conjugated linoleic acid (CLA). F_9,12, 95% pure, was synthesized from methyl ricinoleate. The synthetic F_9,12 was heated at 50°C in sealed tubes containing air. Each tube contained 6 mg F_9,12 and 1 mg methyl stearate as an internal standard. Samples were taken at 4.5, 7, 23, 46.5, 69.5, and 93 h. The oxidized F_9,12 was dissolved in isooctane and analyzed by gas chromatography (GC), GC-direct deposition-Fourier transform infrared spectroscopy, and GC-electron ionization mass spectrometry. CLA methyl ester was oxidized in a similar manner. Under these conditions, the half-lives of CLA and F_9,12 were 40 and 35 h, respectively. Oxidation products of F_9,12 that were identified included: 5-hexyl-2-furaldehyde (I), methyl 8-oxooctanoate (II), methyl 13-oxo-9,12-epoxytrideca-9,11-dienoate (III), methyl 8-oxo-9,12-epoxy-9,11-octadecadienoate (IV), and methyl 13-oxo-9,12-epoxy-9,11-octadecadienoate (V).     

Ultrasound in fatty acid chemistry: Synthesis of a 1-pyrroline fatty acid ester isomer from methyl ricinoleate

A novel 1-pyrroline fatty acid ester isomer [viz. 8-(5-hexyl-1-pyrrolin-2-yl)octanoate] has been synthesized from methyl ricinoleate by two routes with an overall yield of 42 and 30%, respectively. Most of the reactions are carried out under concomitant ultrasonic irradiation (20 KHz,ca. 53 watts/cm²). Under such a reaction condition, the reaction time is considerably shortened, and product yields are high. Dehydrobromination under concomitant ultrasonic irradiation of methyl 9,10-dibromo-12-hydroxyoctadecanoate with KOH in EtOH furnishes methyl 12-hydroxy-9-octadecynoate (66%) within 15 min. Hydration of the latter under ultrasound with mercury(II)acetate in aqueous tetrahydrofuran yields exclusively methyl 12-hydroxy-9-oxo-octadecanoate (95%) in 30 min. The hydroxy group in the latter compound is transformed to the azido functionvia the mesylate, and treatment of the azido-oxo intermediate (methyl 12-azido-9-oxooctadecanoate) with Ph₃P under ultrasonic irradiation furnishes the requisite 1-pyrroline fatty acid ester (77%). The same azido-oxo intermediate has also been obtained by the oxidation of methyl 12-azido-9-cis-octadecenoate using benzoquinone and a catalytic amount of Pd(II)chloride in aqueous tetrahydrofuran under concomitant ultrasonic irradiation (90 min) to give the product in 45% yield. The latter reaction does not take place even under prolonged silent stirring of the reaction mixture.     

Preparation and some spectroscopic properties ofN-heterocyclic derivatives of a novel 1-pyrroline C18 fatty ester

A C₁₈ 1-pyrroline fatty ester, methyl 8-(5-hexyl-2-pyrrolin-1-yl)octanoate (1), was prepared from methyliso-ricinoleate. The C=N bond of the pyrroline ring was oxidized bym-chloroperoxy-benzoic acid to yield a mixture of oxaziridine isomers 2a,2b, which decomposed during gas chromatographic analysis to a 2,5-disubstituted pyrrole derivative, methyl 8-(5-hexyl-1H-pyrrole-2-)octanoate (3). Compound 3 was also obtained by reaction of 2a,2b with dilute HCl in methanol. Reaction of compound 1 with iodo-methane formed anN-methyl iminium iodide intermediate 4, which on reduction with sodium borohydride furnished a mixture ofcis/trans-N-methyl-2,5-disubstituted pyrrolidine derivatives, methyl 8-(cis/trans-5-hexyl-N-methyl-pyrrolidine-2-)octanoates 5a,5b. Reduction of compound 1 with NaBH₄ gave a mixture ofcis/trans-isomers of 2,5-disubstituted pyrrolidine derivatives, methyl 8-(5-hexyl-pyrrolidine-2-)octanoates 6a,6b. Acetylation of compounds 6a,6b with acetic anhydride furnished the correspondingN-acetyl pyrrolidines 7a,7b. When compound 1 was treated with perchloric acid, the corresponding iminium perchlorate derivative, methyl 8-(5-hexyl-1-pyrrolinium perchlorate-2-)octanoate 8 was obtained. The structures of the various derivatives were characterized by a combination of chromatographic, mass spectral and spectroscopic techniques.     

New Nortriterpenoid and Ceramides From Stems and Leaves of Cultivated <Emphasis Type="Italic">Triumfetta cordifolia</Emphasis> A Rich (Tiliaceae)

To highlight the role of plants in traditional healing, the leaves and the stems of cultivated Triumfetta cordifolia were phytochemically studied yielding a new nor-ursane type (1), a new ceramide (2) and a new piperidinic ceramide derivative (3) named, respectively, 2α,19α-dihydroxy-3-oxo-23-nor-urs-12-en-28-oic acid, (2R)-2-hydroxy-N-[(2S,3S,4R,26E)-1,3,4-trihydroxy-26-triaconten-2-yl] tetradecanamide and (2R,8Z)-2-hydroxy-{(2S,3R,5R,6S)-3,5-dihydroxy-6-[(1E,5Z)-hexadeca-1,5-dienyl]-2-(β-d-glucopyranosyloxy)methyl piperidine-1-yl} tetracos-8-enamide (3). These were obtained together with lupeol (4), stigmasterol (5), 3-O-β-d-glucopyranoside of β-sitosterol (6), tormentic acid (7) from stems and heptadecanoic acid (8), β-carotene (9), oleanolic acid (10), and 24-hydroxytormentic acid (11) from leaves. The structures were determined on the basis of NMR data (¹H-, ¹³C-, 2D-NMR analyses), mass spectrometry and confirmed by chemical transformations as well as comparison of spectral data with those reported in the literature. The FRAP method was used to evaluate the antioxidant activity of fractions collected from flash chromatography and isolated compounds. Among the fractions, four reduced Fe^III-TPTZ to Fe^II-TPTZ while isolated pure compounds showed no activity.     

An efficient ultrasound-assisted zinc reduction of fatty esters containing conjugated enynol and conjugated enynone systems

Reduction of methyl 8-hydroxy-11-E/Z-octadecen-9-ynoate (1) with zinc in either aqueous n-propanol or water under concomitant ultrasound irradiation furnished a mixture of methyl 8-hydroxy-9Z,11E-octadecadienoate (3a) and methyl 8-hydroxy-9Z, 11Z-octadecadienoate (3b) (96% yield). Reduction of methyl 8-oxo-11-E/Z-octadecen-9-ynoate (2) under similar conditions gave methyl 8-oxo-10-Z-octadecenoate exclusively (4, 70%). The latter compound was epoxidized and converted to a C₁₈ furanoid fatty ester (6, methyl 8,11-epoxy-8,10-octadecadienoate) in 70% yield.     

Hydrogen sulfide adducts of methyl oleate and linoleate

Sulfur compounds derived from photochemical addition of hydrogen sulfide to methyl oleate and linoleate were separated by preparative gas chromatography. The major compounds were investigated by NMR, mass and IR spectroscopy and by elemental analysis. The primary product of the methyl oleate reaction was methyl 9(10)-mercaptostearate. Gas chromatograms of the product from methyl linoleate showed four principal peaks. From mass spectra and NMR data, we identified methyl 9-(2-pentyl-1-thiolan-5-yl)nonanoate, methyl 8-(2-hexyl-1-thiolan-5-yl)octanoate and methyl 9-(3-hexyl-1,2-dithiolan-5-yl)nonanoate. Evidence for the formation of methyl mercapto-octadecenoates and methyl dimercaptostearates was also obtained. ARS, USDA.     

Radical Scavenging Activity and Performance of Novel Phenolic Antioxidants in Oils During Storage and Frying

Novel phenolic antioxidants: 2a (6′-hydroxy-2′,5′,7′,8′-tetramethylchroman-2′-yl)methyl 3-methoxy-4-hydroxycinnamate, 2b (6′-hydroxy-2′,5′,7′,8′-tetramethylchroman-2′-yl)methyl 3,5-dimethoxy-4-hydroxycinnamate, 2c (6′-hydroxy-2′,5′,7′,8′-tetramethylchroman-2′-yl)methyl 3,4-dihydroxycinnamate, and 3 (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)methyl (6′-hydroxy-2′,5′,7′,8′-tetramethylchroman-2′-carboxylate) have been prepared in good yields and fully characterized by ¹H and ¹³C NMR, and HRMS. Their radical scavenging activities have been evaluated by DPPH and ORAC assays. Each of the synthesized antioxidants exhibited significantly higher radical scavenging activities than trolox and α-tocopherol. These novel antioxidants efficiently protected canola oil triacylglycerides (CTG) during accelerated storage and frying. Compounds 2c and 3 were significantly more efficient than α-tocopherol protecting CTG under accelerated storage. All new antioxidants were more efficient than α-tocopherol under frying conditions and present significantly higher thermal stability.     

Novel functionalized monomers based on kojic acid: snythesis,characterization, polymerization and evalution of antimicrobial activity

Two novel acrylate monomers, [5-(benzyloxy)-4-oxo-4H-pyran-2-yl]methyl acrylate and {1-[(5-(benzyloxy)-4-oxo-4H-pyran-2-yl)methyl]-1,2,3-triazol-4-yl}methyl acrylate were synthesized by the reaction of 5-benzyloxy-2-(hydroxymethyl)-4H-pyran-4-one and 5-(benzyloxy)-2-{[4-(hydroxymethyl)-1,2,3-triazol-1-yl]methyl}-4H-pyran-4-one with acryloyl chloride in the presence of triethylamine, respectively. These monomers were polymerized using 2,2^′-azobisisobutyronitrile (AIBN) as the initiator in N,N-dimethylformamide:14-dioxane (10:1) solution. The thermal behavior of the polymers was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The synthesized compounds were evaluated for their antibacterial and antifungal activites aganist bacteria and fungi using the disk diffusion method. The results indicated that some of these compounds demonstrated moderate to good antibacterial and antifungal activities.     

Oxidation reactions of acetylenic fatty esters with selenium dioxide/tert-butyl hydroperoxide

Reaction of methyl undec-10-ynoate (1) with selenium dioxide/tert-butyl hydroperoxide (TBHP) in aqueous dioxane gave methyl 9-oxo-undec-10-ynoate (2, 9%) and 9-hydroxy-undec-10-ynoate (3, 60%), while methyl octadec-9-ynoate (4) yielded mixtures of positional isomers of mono-keto (viz. methyl 8-oxo- and 11-oxo-octadec-9-ynoate, 5, 5%), hydroxy-keto (viz. methyl 8-hydroxy-11-oxo-and 11-hydroxy-8-oxo-octadec-9-ynoate, 6, 10%), and dihydroxy (viz. methyl 8,11-dihydroxy-octadec-9-ynoate, 7, 24%) derivatives. Similar treatment of a conjugated diacetylenic fatty ester (methyl octadeca-6,8-diynoate, 8) furnished a mixture of methyl 5-oxo-and 10-oxo-octadeca-6,8-diynoate (9, 12%) and a complex mixture of very polar products. Reaction of methyl octadec-11E-en-9-ynoate (methyl santalbate) (10) with selenium dioxide/TBHP in aqueous dioxane gave exclusively a mixture of regiospecific products, viz. methyl 8-oxo-octadec-11(E) Z-en-9-ynoate (11, 6%) and methyl 8-hydroxy-octadec-11 E-en-9-ynoate (12, 70%). The structures of the various products were determined by a combination of spectroscopic and mass spectral analyses.     

Preparation of deuterated methyl 6,9,12-octadecatrienoates and methyl 6,9,12,15-octadecatetraenoates

Methyl 6,9,12-octadecatrienoate-15,15,16,16-d ₄ was obtained by Wittig coupling between 6,6,7,7-tetradeutero-3-nonenyltriphenylphosphonium iodide, 8, and the aldehyde ester, methyl 9-oxo-6-nonenoate. Methyl 6-oxohexanoate, obtained by ozonolysis of cyclohexene, was coupled in a Wittig reaction with [2-(1,3-dioxan-2-yl)ethyl]triphenylphosphonium bromide to give methyl 8-dioxanyl-6-octenoate. This compound was transacetalized to methyl 9,9-dimethoxy-6-nonenoate, which was then hydrolyzed to the aldehyde ester. For the preparation of compound 8, the tetrahydropyranyl ether of 2-pentynol was deuterated with deuterium gas and tris-(triphenylphosphine)chlororhodium. The tetradeuterated tetrahydropyranyl ether was converted to the bromide with triphenylphosphine dibromide, and the bromide was coupled with 3-butynol by means of lithium amide in liquid ammonia to give 3-nonynol-6,6,7,7-d ₄. Hydrogenation over Lindlar's catalyst converted the deuterated alkynol to 3-nonenol-6,6,7,7-d ₄. This deuterated alkenol was converted to the bromide with triphenylphosphine dibromide, then to the iodide with sodium iodide in acetone, and finally to 8 with triphenylphosphine in acetonitrile. Methyl 6,9,12,15-octadecatetraenoate-12,13,15,16-d ₄ was obtained by Wittig coupling between methyl 9-oxo-6-nonenoate and 3,4,6,7-tetradeutero-3,6-nonadienyltriphenylphosphonium iodide, 15. For the preparation of compound 15, the bromide obtained from the reaction of 2-pentynol with triphenylphosphine dibromide was coupled with 3-butynol with lithium amide in liquid ammonia. The resulting 3,6-nonadiynol was deuterated with deuterium gas in the presence of P-2 nickel, and the resultant deuterated nonadienol was converted to 15 through the bromide and iodide. The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.     

cryoEM-Guided Development of Antibiotics for Drug-Resistant Bacteria

While the ribosome is a common target for antibiotics, challenges with crystallography can impede the development of new bioactives using structure-based drug design approaches. In this study we exploit common structural features present in linezolid-resistant forms of both methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) to redesign the antibiotic. Enabled by rapid and facile cryoEM structures, this process has identified (S)-2,2-dichloro-N-((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)acetamide (LZD- 5 ) and (S)-2-chloro-N-((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl) acetamide (LZD- 6 ), which inhibit the ribosomal function and growth of linezolid-resistant MRSA and VRE. The strategy discussed highlights the potential for cryoEM to facilitate the development of novel bioactive materials.     

Reaction of mono-epoxidized conjugated linoleic acid ester with boron trifluoride etherate complex

The reaction of methyl 11, 12-E-epoxy-9Z-octadecenoate (1) with boron trifluoride etherate furnished a mixture of methyl 12-oxo-10E-octadecenoate (3a) and methyl 11-oxo-9E-octadecenoate (3b) in 66% yield. Methyl 9, 10-Z-epoxy-11 E-octadecenoate (2) with boron trifluoride etherate furnished a mixture of methyl 9-oxo-10 E-octadecenoate (4a, 45%) and methyl 10-oxo-11 E-octadecenoate (4b, 19%). A plausible mechanism is proposed for these reactions, which involves the attack on the epoxy ring system by BF₃, followed by deprotonation, oxo formation, and double bond migration to give a mixture of two positional α,β-unsaturated C₁₈ enone ester derivatives (3a/3b, 4a/4b). The structures of these C₁₈ enone ester derivatives (3a/3b, 4a/4b) were identified by a combination of NMR spectroscopic and mass spectrometric analyses.     

Bornane with integrated push–pull butadienes

The {3-[bis(alkylthio)methylene]-1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylidene}malononitriles ((1R,4S)- 2 , (1S,4R)- 2 and (1R,4S)- 3 ) were prepared starting from 1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylidenemalononitriles (1R, 4R)- 1 and (1S,4S)- 1 ) arisen from (+)-, (–)-camphor. The reaction of (1R,4S)- 2 with bromine yielded the (1S,8R)-8,11,11-trimethyl-3-methylthio-5-oxo-4-thiatricyclo-[6.2.1.0^2,7]undeca-2,6-diene-6-carbonitrile ( 8 ) after hydrolysis of the initially formed (1S,8R)-6-cyano-8,11,11-trimethyl-3-methylthio-4-thia-tricyclo[6.2.1.0^2,7]undeca-2,6-diene-5-iminium bromide ( 7 ).     

Electrochemical behavior of a new <Emphasis Type="Italic">s</Emphasis>-triazine-based dendrimer

The electrochemical behavior of a new G-2-s-triazine-based dendrimer, 2,4,6-tris-{4-{4,6-bis-{4-{4,6-bis-[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-s-triazin-2-yl}-piperazin-1-yl}-s-triazine, (I), was studied in dimethylsulfoxide solution by cyclic voltammetry, on platinum and graphite electrodes. The electrochemical properties of I were compared with that of one of its precursor, N-{4,6-bis{4-{4,6-bis[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-triazin-2-yl}-piperazine), (II), together with that of the starting material, (1S,2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol (“p-nitrophenylserinol”), (III).     

Synthesis,Characterization and Anti-Breast Cancer Activity of New 4-Aminoantipyrine-Based Heterocycles

4-Aminoantipyrine was utilized as key intermediate for the synthesis of pyrazolone derivatives bearing biologically active moieties. The newly synthesized compounds were characterized by IR, ¹H- and ¹³C-NMR spectral and microanalytical studies. The compounds were screened as anticancer agents against a human tumor breast cancer cell line MCF7, and the results showed that (Z)-4-((3-amino-5-imino-1-phenyl-1H-pyrazol-4(5H)-ylidene)methylamino)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 5, 3-(4-bromophenyl) -1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 13, 1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1-Hpyrazol- 4-yl)-3-(4-iodophenyl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 14, 3,3′-(4,4′-sulfonylbis(4,1-phenylene))bis(1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol- 4-yl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile) 16, (Z)-1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-hydrazono-4-oxo-3-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 17, (Z)-1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-4-oxo-3-phenyl-2-(2-phenylhydrazono)-1,2,3,4-tetrahydro pyrimidine-5-carbonitrile 18, and (Z)-4-(3-amino-6-hydrazono-7-phenyl-6,7-dihydro pyrazolo[3,4-d]pyrimidin-5-yl)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 19 were the most active compounds with IC₅₀ values ranging from 30.68 to 60.72 μM compared with Doxorubicin as positive control with the IC₅₀ value 71.8 μM.     

Short and Simple Syntheses of 4-Oxo-(<Emphasis Type="Italic">E</Emphasis>)-2-Hexenal and Homologs: Pheromone Components and Defensive Compounds of Hemiptera

One-step syntheses of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal from commercially available 2-ethyl- and 2-butylfuran are described. A two-step synthesis of the homolog 4-oxo-(E)-2-decenal from furan is also reported. These compounds are common components of true bug defensive secretions, and recently have been identified as pheromone components for several species. The simple syntheses reported here will make these compounds readily available for further research.     

Thiation of new 5-(2-aryl-2-oxoethyl)-2,4-dioxo-1, 3-thiazolidines

Abstract

The hitherto unknown 5-(2-aryl-2-oxoethyl)-3-substituted-2,4-dioxo-1,3-thiazolidines 2 and 5-(2-aryl-2-oxoethylidene)-3-aryl-2,4-dioxo-1,3-thiazolidines 4 have been prepared from their 2-thioxo- homologues 1 and 3, respectively, via treatment with CrO₃. Compound 4 has also been obtained by treating 1 and/or 2 with bromine at different experimental conditions. Thiation of 2 and/or 4, gave a mixture of 3,5-di-substituted-2,3-dihydro-2-oxothieno[2,3-d]thiazoles 5 and the respective 2-thioxo derivatives 6. Reactions of hydrazine hydrate with 1c, d, were carried out at room temperature as well as under reflux, affording di-(3-oxo-6-aryl-4,5-dihydropyridazin)disulfides 7c, d and di-(3-oxo-6-arylpyridazin)disulfides 8c, d, respectively, together with 4-arylthiosemi carbazides 9c, d, under both conditions. Structures of the above products have been elucidated based on their microanalytical and spectroscopic data. Compound 2e exhibited pronounced antischistosomal activity.