Mixture Of Cis Research Articles

Technical note: Improved synthetic routes to cis- and trans-(2-methyloxirane-2,3-diyl)dimethanol (cis- and trans-β-isoprene epoxydiol)

Abstract. We report improved synthetic routes to the isomeric isoprene-derived β-epoxydiols (β-IEPOX) in high yield (57 %–69 %) from inexpensive, readily available starting compounds. The syntheses do not require the protection/deprotection steps or time-consuming purification of intermediates and can readily be scaled up to yield the target IEPOX isomers in gram quantities. Emissions of isoprene (2-methyl-1,3-butadiene, C5H8), primarily from deciduous vegetation, constitute the largest source of nonmethane atmospheric hydrocarbons. In the gas phase under low-nitric-oxide (NO) conditions, addition of the atmospheric hydroxyl radical (OH) followed by rapid addition of O2 yields isoprene-derived hydroxyperoxyl radicals. The major sink (>90 %) for the peroxyl radicals is a sequential reaction with the hydroperoxyl radical (HO2), OH, and O2, which is then followed by the elimination of OH to yield a ∼2:1 mixture of cis- and trans-(2-methyloxirane-2,3-diyl)dimethanol (cis- and trans-β-IEPOX). The IEPOX isomers account for about 80 % of closed-shell hydroxyperoxyl products and are rapidly taken up into acidic aerosols to form secondary organic aerosol (SOA). IEPOX-derived SOA makes a significant mass contribution to fine particulate matter (PM2.5), which is known to be a major factor in climate forcing as well as adversely affecting respiratory and cardiovascular systems of exposed populations. Prediction of ambient PM2.5 composition and distribution, both in regional- and global-scale atmospheric chemistry models, crucially depends on the accuracy of identification and quantitation of uptake product formation. Accessibility of authentic cis- and trans-β-IEPOX in high purity and in large quantity for laboratory studies underpins progress in developing models as well as identification and quantitation of PM2.5 components.

Complexes of Crown Ethers with Diaminomaleodinitrile

1,2-Diaminomaleodinitrile (HCN tetramer) is usu-ally considered as one of the key steps of chemicalevolution [1 4] on the pathway of transformation ofhydrogen cyanide into amino acids and heterocycles[4 6]. According to [7, 8], in simulation of biochem-ical processes, it is important to reveal noncovalentinteractions of relatively small molecules with cavity-containing structures, in particular, with crown ethers.The goal of this work was to examine the possibil-ity of preparing crystalline molecular complexes ofcrown ethers with 1,2-diaminomaleodinitrile and toreveal the selectivity of such host guest interactions.We found that spontaneous evaporation of solventsfrom solutions of crown ethers [benzo-15-crown-5,I;18-crown-6,II; benzo-18-crown-6,III; mixture ofcis,syn,cis (IV) and cis,anti,cis (V) isomers of dicyclo-hexano-18-crown-6] with 1,2-diaminomaleodinitrileVI results in crystalllization of molecular complexesVII X.

Reactions of sulfenamides with alkynes in the presence of phosphorus(v) oxohalides

The reactions of alkynes with arylsulfenamides activated with phosphorus oxohalides giving rise to aryl β-halovinyl sulfides were investigated. The reactions with acetylene, oct-1-yne, and oct-4-yne aretrans-stereospecific, whereas the reaction with phenylacetylene afforded a mixture ofcis- andtrans-addition products. The addition to unsymmetrical alkynes yielded a mixture of Markovnikoff and anti-Markovnikoff isomers whose ratio depends on the solvent. Products of addition to oct-1-yne in the presence of catalytic amounts of acids underwent isomerization.

Microbial Conversion of Indene to Indandiol: A Key Intermediate in the Synthesis of CRIXIVAN

Indene is oxidized to mixtures ofcis- andtrans-indandiols and related metabolites byPseudomonas putidaandRhodococcussp. isolates. Indene metabolism is consistent with monooxygenase and dioxygenase activity.P. putidaresolves enantiomeric mixtures ofcis-1,2-indandiol by further selective oxidation of the 1R, 2S-enantiomer yielding high enantiomeric purity ofcis-(1S, 2R)-indandiol, a potential intermediate in the synthesis of indinavir sulfate (CRIXIVAN), a protease inhibitor used in the treatment of AIDS. Molecular cloning ofP. putidatoluene dioxygenase inEscherichia coliconfirmed the requirement for the dihydrodiol dehydrogenase in resolving racemic mixtures ofcis-indandiol.Rhodococcussp. isolates convert indene tocis-(1S, 2R)-indandiol at high initial enantiomeric excess and one isolate also producestrans-(1R, 2R)-indandiol, suggesting the presence of monooxygenase activity. Scale up and optimization of the bioconversions to these key synthons for chiral synthesis of potential intermediates for commercial manufacture of indinavir sulfate are described.

Stereochemistry of addition of mercury salts to alkynes

Reactions of Hg(OOCR)2 (R=Et, Prn, Pri, and Bun) with methylphenylacetylene (with the corresponding acids as solvents) give mixtures ofcis- andtrans-adducts. The quantity of thecis-adduct increases with increase in the length of the acyl substituent.syn-Addition also occurs in the acetoxymercuration ofm-chlorophenyl(methyl)acetylene and 1-methoxybut-2-yne; in the latter case, this route predominates. The stereochemistry of the reaction can also depend on the ratio of the reactants. It is proposed that the reaction occurs by several schemes in which these factors manifest themselves in different degrees.

Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane with acetonitrile

Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane (a mixture ofcis- andtrans-isomers in a 81 : 19 ratio) with acetonitrile yielded 2,5-dimethyl-4-phenyl-5,6-dihydro1, 3-oxazine as a mixture ofcis- andtrans-forms in a 50 : 50 ratio. The possible mechanism of this transformation is discussed.

Catalytic asymmetric synthesis of polysubstituted cyclohexa-1,3-dienes from ?-branched ?,?-alkenals

3-Methyl- and 3-phenylbut-2-enal in the presence of (S)-prolinol (0.1 eq.) in benzene or THF react with the acidic monoesters of alkenylidene, and arylmethylidene-, and alkylidenemalonic acids at −10 to +22 °C to give optically active esters of 4,6-disubstituted cyclohexa-1,3-diene-l-carboxylic acids in moderate (10–43 %) yields. The enantiomeric purity of the products formed from the lint two types of acidic ylidenemalonates varies from 28 to 68 % and is higher than that observed in the case of related alkylidenemalonates. Under similar conditions cyclohexylideneacetaldehyde affords optically active derivatives of 1,5,6,7,8,8a-hexahydronaphthalene as mixtures ofcis andtrans isomers. The enantiomeric purity and absolute configuration of the cyclohexadienes thus obtained were determined using1H NMR spectroscopy in combination with chiral solvating agents.

Isomerization of substituted tricyclic 4,5-dihydropyrazoles

The acid and base catalyzed isomerization of some tricyclic 2-pyrazolines with N-Carbamoyl-,N-thiocarbamoyl-and N-phenyl substituents was investigated. Starting fromcis ortrans 3-H, 3a-H diastereomers, equilibrium mixtures ofcis andtrans diastereomers were prepared which were separated and subsequently studied by1H NMR and13C NMR spectroscopy. A mechanism for the isomerization of the pyrazolines is suggested, supported by a deuterium exchange at C-3a.

Palladium(II) and platinum(II) complexes with N-substituted methionines

As an approach to systems containing methionine residues, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (HDh, dehydroacetic acid) was treated with L-methionine (MetH) or L-methionine methylester (MetM). By condensation at the acyl group and transfer of the phenolic hydrogen on the nitrogen atom, the related ligands DhMetH and DhMetM, were isolated, and form complexes of formula [MX2(L)2](M = Pd or Pt, L = DhMetM, X = Cl, Br or I; L = DhMetH, X = Cl or Br) and [MI2(DhMetH)] with palladium and platinum dihalides. The reaction of the DhMetK carboxylate with MCl2 in various media is discussed. Ligands and complexes were characterized by i.r. and n.m.r. (1H and13C) spectroscopy and, in some cases, by thermogravimetric measurements. The ligands behave as monodentate sulphur donors, the 1∶2 complexes showing atrans geometry except for [PtCl2(DhMetH)2], which is probably a mixture ofcis andtrans isomers.

Hydrogenation of 6- and 7-alkyl-2-(4?-bromophenyl)indolizines

Hydrogenation of 6- and 7-alkyl-2-(4′-bromophenyl)indolizines over rhenium heptasulfide proceeds with hydrodebromination to give a mixture ofcis- andtrans-isomers of 6- and 7-alkyl-2-phenylindolizidines.

Synthesis and characterization of palladium(II) complexes of some tellurium heterocycles

A series of square planar complexes of the type [PdX2L2] where X=Cl, Br, I; L=telluracyclopentane (tcp), telluracyclohexane (tch) or benzotelluracyclopentane (btp) have been synthesised. The complexes were characterised by far-i.r., n.m.r. and u.v.-vis. spectroscopy. The data implytrans-geometries except for the complex [PdCl2(tch)2] where a mixture ofcis- andtrans-isomers is obtained.

The preparation and characterisation of chromium(III) complexes of C-meso-5, 12-dimethyl-1, 4, 8, 11-tetraazacyclotetradecane (LM). Aquation and base hydrolysis kinetics ofcis- andtrans-[CrLMCl2

The reaction of [CrCl3(DMF)3] with C-meso-5, 12-dimethyl-1, 4, 8, 11-tetra-azacyclotetradecane(LM) in DMF gives a mixture ofcis-[CrLMCl2]Cl (ca. 90%) andtrans-[CrLMCl2]Cl (ca. 10%). These complexes are readily separated, as thecis-isomer is insoluble in warm methanol while thetrans-isomer is soluble. Using the dichlorocomplexes as precursors it has been possible to prepare a range ofcis-[CrLMX2]+ complexes (X=Br−, NO3−, N3−, NCS− and X2=bidentate oxalate) and alsotrans-[CrLMX2]+ complexes (X=Br−, H2O or NCS−). The spectroscopic properties and detailed stereochemistry of the complexes are discussed.

Heat treatment of vegetable oils III. GC‐MS characterization of cyclic fatty acid monomers in heated sunflower and linseed oils after total hydrogenation

AbstractFractions of cyclic fatty acid monomers (CFAM) were isolated from linseed oil heated at 275°C for 12 hr under nitrogen, at 240°C for 10 hr under nitrogen and at 240°C for 10 hr under air. Cyclic fatty acid monomers fractions were also isolated from a sunflower oil heated at 275°C for 12 hr under nitrogen and at 200°C for 48 hr in a commercial fryer. The CFAM fractions were hydrogenated and their composition studied by gas liquid chromatography coupled with mass spectrometry (GC‐MS). The CFAM in the fraction isolated from heated linseed oil samples were a mixture (1:1) ofcis andtrans cyclopentyl and cyclohexyl isomers, while the CFAM in the fractions isolated from heated sunflower oils were mostly cyclopentyl isomers. The major cyclopentyl isomers weretrans andcis methyl 7‐(2′‐hexylcyclopentyl) ‐heptanoate, methyl 9‐(2′‐butyl‐cyclopentyl)‐nonanoate and methyl 10‐(2′‐propylcyclo‐pentyl)‐decanoate. The major cyclohexyl isomers were thetrans andcis methyl 9‐(2′‐propylcyclohexyl)‐nonanoate which represented about 50% of the CFAM isomers isolated from heated linseed oil samples.

Kinetics and mechanisms of the reactions of thiosulphato-amine complexes of cobalt(III). Part II. Base hydrolysis of the bis(ethylenediamine)thiosulphatocobalt(III) ion

Base hydrolysis of the bis(ethylenediamine)thiosulphatocobalt(III) was investigated spectrophotometrically between 35 and 65 °C and with base concentrations (NaOH) up to 2.0 mol dm−3. The hydrolysis consists of a one-stage reaction, followed by a slow dechelation step, and then by a fast ligand loss. The reaction is base-dependent. The products of the reaction are an equilibrium mixture ofcis- andtrans-Coen2 (OH) 2 + . Activation parameters for the reaction as determined by the Eyring equation, are ΔH†=77.8±4.6 kJ mol−1 and ΔS†=−75±20 JK−1 mol−1.

Partial argentation resin chromatography (PARC): I. Effect of percent silver on elution and separation of methyl octadecadienoate isomers

AbstractPartial argentation resin chromatography (PARC) for the separation of octadecadienoate ester isomers was investigated. In comparison to saturated silver resin chromatography, the time necessary to elute methylcis,cis‐octadecadienaotes was dramatically shortened when columns containing sulfonic acid ion exchange resin silvered in the range of 60~90% of theoretical (meaning 60~90% of the sulfonic acid protons in the resin were replaced by silver ions) were used. Methods for preparation and silvering of the resin are discussed. The XN1010 resin (Rohm and Haas) was analyzed for total sulfonic acid groups and the amount of silver that can be incorporated by one or 2 treatments with silver nitrate was determined. A series of partially silvered resin columns was prepared and samples of methyl linoleate were eluted to study the effect of the percentage silvering on elution volumes and peak shapes. Twenty‐gram samples of mixtures ofcis,trans‐ andtrans,trans‐ and oftrans,cis‐ andcis,cis‐methyl 12,15‐octadecadienoates were separated on a 91% PARC (91% silvered) column.

Behavioral responses of the female eastern spruce budwormChoristoneura fumiferana (Lepidoptera, Tortricidae) to the sex pheromone of her own species

Female eastern spruce budworm moths respond to the synthetic sex pheromone of their own species (a mixture ofcis- andtrans-11-tetradecenal) by walking, antennal grooming, flexation of the body, extension of the ovipositors, and oviposition. The sex pheromone is perceived by receptors on the antennae. Electroantennogram responses from the female are approximately two-thirds the amplitude of those obtained from males.

The application of packed column gas chromatographic analysis to the determination oftrans unsaturation

Abstract and summaryA study of the separation of synthetic mixtures ofcis andtrans methyl octadecenoate with packed column gas chromatography indicated its usefulness for such analyses. Several margarines were analyzed by this method and the results compared with those obtained by the infrared spectroscopic method. Reasonable agreement between both methods was obtained, but the gas chromatographic determination yielded lower values (average 3.8%). The presence oftrans unsaturation was also shown in selected samples of human milk and blood lipids.

Derivatives of long chain fatty acids as lubricant components

AbstractSoaps ofcis‐9,10‐epiminostearic acid have been synthesized and tested as components of lubricating greases. The lithium, sodium and potassium soaps were obtained by the reaction ofβ‐iodocarbamates with the proper alkali metal hydroxides in the ring closure step of the iodine isocyanate (INCO) procedure for the synthesis of internal aziridines. The soaps of other metals, namely barium, lead, aluminum and indium, were prepared from the alkali metal epiminostearates by metathetical reactions. As a result of this method of preparation, the aluminum and the indium soaps were isolated as the dicarboxylates rather than as the tricarboxylates. For the purpose of comparison a sample of lithium 9,10‐epiminostearate was also prepared from theβ‐chlorocarbamate obtained by the addition of dichlorourethane (DCU) to methyl oleate. Since DCU addition is nonstereospecific, the soap obtained in this preparation was a mixture ofcis‐ andtrans‐aziridines. Evaluation of the metal soaps as grease thickeners was made. The lithium derivative showed considerable promise as thickener having additional desirable properties.

Synthesis of long chaina,B‐alkynoic anda,B‐alkynoic acids viaB‐keto esters

AbstractA general method for the synthesis of long chain α,β‐alkynoic acids from β‐keto esters is described. The synthesis involves conversion of the β‐keto ester to the corresponding pyrazolone, then halogenation and treatment of the resultant 4,4‐dihalo product with dilute aqueous alkali to form the α,β‐alkynoic acids. Specifically, 2‐octynoic, 2‐nonynoic and 2‐decadecynoic acids were prepared as representative examples. If the β‐keto ester has an alkyl group at the α‐position, the final product is a mixture ofcis andtrans α‐substituted‐α,β‐unsaturated alkenoic acids, which may be separated by gas‐liquid chromatography. Pertinent IR and proton magnetic resonance data are used in characterizing the stereochemistry of products and a possible mechanism for the product forming reactions is presented.

Preparation of epiminostearates. Comparison of methods

AbstractThe addition of N,N‐dichlorourethan (DCU) to internal olefins has been found to be an acceptable reaction leading to the preparation of internal fatty acid aziridines. The yields of isolated epimino derivatives are in the 50–60% range, only slightly lower than those obtained by the iodine isocyanate (INCO) method. In order to compare the stereochemistry of the two methods, an IR spectroscopic procedure was developed which permits an estimation of the relative amounts ofcis‐ andtrans‐aziridines in mixtures of the two. In agreement with literature reports, the INCO method is stereospecific, thecis‐olefins giving rise tocis‐aziridines and thetrans‐olefins formingtrans‐aziridines. On the other hand, DCU addition to olefins results in mixtures ofcis‐ andtrans‐aziridines in which the latter isomers predominate. This finding is compatible with the reported free‐radical nature of the DCU reaction.